for more information on the mlp revolver , please see `` liquidity and capital resources—indebtedness—mlp revolver . `` how we generate revenue we generate revenue primarily by selling ethylene and the resulting co-products we produce . in connection with the ipo , opco and westlake entered into an ethylene sales agreement ( the `` ethylene sales agreement `` ) pursuant to which we generate a substantial majority of our revenue . the ethylene sales agreement is a long-term , fee-based agreement with a minimum purchase commitment and includes variable pricing based on opco 's actual feedstock and natural gas costs and estimated other costs of producing ethylene ( including opco 's estimated operating costs and a five-year average of opco 's expected future maintenance capital expenditures and other turnaround expenditures based on opco 's planned ethylene production capacity for the year ) , plus a fixed margin per pound of $ 0.10 less revenue from co-products sales . pursuant to the ethylene sales agreement , westlake 's obligation to pay for the annual minimum commitment ( 95 % of opco 's budgeted ethylene production ) , which is measured at the end of the year , is generally not reduced for the first 45 days of a force majeure event , but is reduced for the portion of a force majeure event extending beyond the 45th day . westlake has an option to take 95 % of volumes in excess of the minimum commitment on an annual basis under the ethylene sales agreement if we produce more than our planned production . under the ethylene sales agreement , the price for the sale of such excess ethylene to westlake is based on a formula similar to that used for the minimum purchase commitment , with the exception of certain fixed costs . in addition , under the ethylene sales agreement , if production costs billed to westlake on an annual basis are less than 95 % of the actual production costs incurred by opco during the contract year , opco is entitled to recover the shortfall in such production costs ( proportionate to the volume sold to westlake ) in the subsequent year ( `` shortfall `` ) . the shortfall is recognized during the period in which the related operating , maintenance or turnaround activities occur . 28 we sell ethylene production in excess of volumes sold to westlake , as well as all associated co-products resulting from the ethylene production , directly to third parties on either a spot or contract basis . net proceeds ( after transportation and other costs ) from the sales of associated co-products that result from the production of ethylene purchased by westlake are netted against the ethylene price charged to westlake under the ethylene sales agreement , thereby substantially reducing our exposure to fluctuations in the market prices of these co-products . during 2016 , all the third-party ethylene and associated co-products sales generated greater than 13 % of our total revenues . the significant drop in crude oil prices since the third quarter of 2014 and continuing through 2016 may create volatility in the north american and global markets , which may result in further reduced prices and margins in third-party ethylene and such co-products sales in 2017. under the services and secondment agreement , opco uses a portion of its production capacity to process purge gas for westlake . on august 4 , 2016 , opco and westlake entered into an amendment to the ethylene sales agreement in order to provide that certain of the pricing components that make up the price for ethylene sold thereunder would be modified to reflect the portion of opco 's production capacity that is used to process westlake 's purge gas instead of producing ethylene and to clarify that costs specific to the processing of westlake 's purge gas would be recovered under the services and secondment agreement , and not the ethylene sales agreement . please refer to note 2 to the consolidated and combined financial statements within this report for more information on the ethylene sales agreement . how we source feedstock in connection with the ipo , opco entered into a 12-year feedstock supply agreement ( the `` feedstock supply agreement `` ) with westlake petrochemicals llc , a wholly owned subsidiary of westlake , under which westlake petrochemicals llc supplies opco with ethane and other feedstocks that opco uses to produce ethylene under the ethylene sales agreement . opco may purchase the ethane and other feedstocks to produce ethylene and resulting co-products to sell to unrelated third parties from westlake petrochemicals llc . please refer to note 2 to the consolidated and combined financial statements within this report for more information on the feedstock supply agreement . how we evaluate operations our management uses a variety of financial and operating metrics to analyze our performance . these metrics are significant factors in assessing our operating results and profitability and include : ( 1 ) production volumes , ( 2 ) operating and maintenance expenses , including turnaround costs , and ( 3 ) mlp distributable cash flow and ebitda . production volumes the amount of profit we generate primarily depends on the volumes of ethylene and resulting co-products we are able to produce at calvert city olefins and lake charles olefins . although westlake has committed to purchasing minimum volumes from us under the ethylene sales agreement , our results of operations are impacted by our ability to : produce sufficient volumes of ethylene to meet our commitments under the ethylene sales agreement or recover our estimated costs through the pricing provisions of the ethylene sales agreement ; contract with third parties for the remaining uncommitted production capacity ; add or increase capacity at our existing production facilities , or add additional production capacity via organic expansion projects and acquisitions ; and achieve or exceed the specified yield factors for natural gas , ethane and other feedstock under the ethylene story_separator_special_tag this increase in interest expense was partially offset by the lower average interest rate for the year ended december 31 , 2016 as compared to the prior year due to the april 2015 repayment of a significant portion of the august 2013 promissory notes ( as defined in `` liquidity and capital resources—indebtedness `` ) , which bear a higher interest rate as compared to our other outstanding debt . 2015 compared with 2014 net sales . net sales decreased by $ 742.5 million , or 42.4 % , to $ 1,007.2 million in 2015 from $ 1,749.7 million in 2014 , primarily due to a lower average sales price of ethylene sold to westlake resulting from the execution of the ethylene sales agreement following the ipo , lower average sales price of ethylene sold to third parties due to the significant decline in market prices in 2015 and a lower volume of ethylene sold to third parties , partially offset by increased volume of ethylene sold to 34 westlake in 2015 as compared to 2014. the total ethylene sales volume in 2015 was lower as compared to 2014 due primarily to westlake 's retention of the predecessor 's ethylene procurement and reselling activities , which was partially offset by higher production in 2015 resulting from the calvert city olefins expansion in 2014 and other efficiency projects . further , co-product sales prices were significantly lower in 2015 as compared to 2014 , primarily due to the significant decline in market prices of coproducts , which resulted in a decrease in co-product sales to third parties . this decrease in sales prices was partially offset by an increase in volume of co-product sales to third parties . additionally , there were no excess feedstock sales subsequent to the ipo in 2014 or in 2015 as such activities were retained by westlake . the overall average sales prices of ethylene and co-products in 2015 decreased by 38.0 % as compared to 2014 and overall sales volumes in 2015 decreased by 4.4 % as compared to 2014. gross profit . gross profit margin percentage decreased to 38.0 % in 2015 from 42.6 % in 2014 primarily due to a reduction in margin for ethylene sold to westlake resulting from the ethylene sales agreement and also due to the decline in margin from ethylene sold to third parties as a result of the significant decline in ethylene market prices during 2015. the decrease was largely offset by a drop in feedstock prices , a decrease in energy costs as well as the absence in 2015 of costs and lost production associated with the calvert city olefins turnaround , conversion and expansion activities that took place during the first and second quarters of 2014. selling , general and administrative expenses . selling , general and administrative expenses decreased by $ 5.7 million , or 19.5 % , to $ 23.6 million in 2015 from $ 29.3 million in 2014. the decrease was mainly attributable to the absence of an allocation from westlake of labor costs attributable to the predecessor 's operations retained by westlake after the ipo , partially offset by incremental selling , general and administrative expenses incurred by the partnership subsequent to the ipo as a result of being a separate publicly-traded partnership . interest expense . interest expense decreased by $ 5.5 million to $ 5.0 million in 2015 from $ 10.5 million in 2014 , primarily due to a lower average interest rate in 2015 as compared to the prior year . the lower average interest rate in 2015 as compared to the prior year was due to the repayment of a significant portion of the august 2013 promissory notes ( as defined in `` liquidity and capital resources—indebtedness `` ) in april 2015 , which bear a higher interest rate as compared to our other outstanding debt . other income , net . other income , net decreased by $ 3.0 million to $ 0.2 million in 2015 from $ 3.2 million in 2014 , primarily due to the absence of income attributable to the predecessor 's equity stake in a natural gas liquids pipeline joint venture that was not contributed to us in connection with the ipo . income taxes . the effective income tax rate was 0.2 % in 2015 as compared to 28.1 % for 2014. the effective income tax rate in 2015 is not comparable to the effective income tax rate for 2014 as the partnership is not subject to federal income taxes subsequent to the ipo . story_separator_special_tag font style= `` font-family : inherit ; font-size:10pt ; `` > the partnership maintains separate bank accounts , but westlake continues to provide treasury services on our behalf under the services and secondment agreement . our sources of liquidity include cash generated from operations , the opco revolver , the mlp revolver and , if necessary and possible under then current market conditions , the issuance of additional equity interests or debt . we believe that cash generated from these sources will be sufficient to meet our short-term working capital requirements and long-term capital expenditure requirements and to make quarterly cash distributions . westlake may also provide other direct and indirect financing to us from time to time , although it is not required to do so . in order to fund non-annual turnaround expenditures , we cause opco to reserve approximately $ 30.0 million during each twelve-month period for turnaround activities . each of opco 's ethylene production facilities requires turnaround maintenance approximately every five years . by reserving additional cash annually , we intend to reduce the variability in opco 's cash flow . westlake 's purchase price for ethylene purchased under the ethylene sales agreement includes a component ( adjusted annually ) designed to cover , over the long term , substantially all of opco 's turnaround expenditures . our cash is generated from cash distributions from opco . opco was a restricted

cash flows operating activities operating activities provided cash of $ 287.7 million in 2016 compared to cash provided of $ 452.5 million in 2015 . the $ 164.8 million decrease in cash flows from operating activities was mainly due to the lake charles petro 1 facility turnaround , which resulted in a net cash use of approximately $ 77.9 million during 2016 as compared to $ 3.5 million of net cash used during 2015 , and an increase in the use of cash for working capital purposes , as compared to the prior year . changes in components of working capital , which we define for the purposes of this cash flow discussion as accounts receivable—westlake , accounts receivable , net—third parties , inventories , prepaid expenses and other current assets less accounts payable—westlake , accounts payable—third parties and accrued liabilities , used cash of $ 89.8 million in 2016 as compared to $ 19.4 million of cash provided during 2015 , resulting in an overall unfavorable change of $ 109.2 million . this change was primarily due to the shortfall recognized as westlake receivable in 2016. operating activities provided cash of $ 452.5 million in 2015 compared to cash provided of $ 604.0 million in 2014. the $ 151.5 million decrease in cash flows from operating activities was mainly due to a decrease in net income from operations as a result of the ethylene sales agreement by $ 155.9 million , partially offset by a decrease in use of cash for working capital purposes .


 Write a concise suspicious activity report of the following text delimited by triple backquotes. Return your response as a formal report which covers the key points highlighting the location,dates,entity names and account holder information in chronological order of the text.
     ```cash flows operating activities operating activities provided cash of $ 287.7 million in 2016 compared to cash provided of $ 452.5 million in 2015 . the $ 164.8 million decrease in cash flows from operating activities was mainly due to the lake charles petro 1 facility turnaround , which resulted in a net cash use of approximately $ 77.9 million during 2016 as compared to $ 3.5 million of net cash used during 2015 , and an increase in the use of cash for working capital purposes , as compared to the prior year . changes in components of working capital , which we define for the purposes of this cash flow discussion as accounts receivable—westlake , accounts receivable , net—third parties , inventories , prepaid expenses and other current assets less accounts payable—westlake , accounts payable—third parties and accrued liabilities , used cash of $ 89.8 million in 2016 as compared to $ 19.4 million of cash provided during 2015 , resulting in an overall unfavorable change of $ 109.2 million . this change was primarily due to the shortfall recognized as westlake receivable in 2016. operating activities provided cash of $ 452.5 million in 2015 compared to cash provided of $ 604.0 million in 2014. the $ 151.5 million decrease in cash flows from operating activities was mainly due to a decrease in net income from operations as a result of the ethylene sales agreement by $ 155.9 million , partially offset by a decrease in use of cash for working capital purposes .
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 Suspicious Activity Report : for more information on the mlp revolver , please see `` liquidity and capital resources—indebtedness—mlp revolver . `` how we generate revenue we generate revenue primarily by selling ethylene and the resulting co-products we produce . in connection with the ipo , opco and westlake entered into an ethylene sales agreement ( the `` ethylene sales agreement `` ) pursuant to which we generate a substantial majority of our revenue . the ethylene sales agreement is a long-term , fee-based agreement with a minimum purchase commitment and includes variable pricing based on opco 's actual feedstock and natural gas costs and estimated other costs of producing ethylene ( including opco 's estimated operating costs and a five-year average of opco 's expected future maintenance capital expenditures and other turnaround expenditures based on opco 's planned ethylene production capacity for the year ) , plus a fixed margin per pound of $ 0.10 less revenue from co-products sales . pursuant to the ethylene sales agreement , westlake 's obligation to pay for the annual minimum commitment ( 95 % of opco 's budgeted ethylene production ) , which is measured at the end of the year , is generally not reduced for the first 45 days of a force majeure event , but is reduced for the portion of a force majeure event extending beyond the 45th day . westlake has an option to take 95 % of volumes in excess of the minimum commitment on an annual basis under the ethylene sales agreement if we produce more than our planned production . under the ethylene sales agreement , the price for the sale of such excess ethylene to westlake is based on a formula similar to that used for the minimum purchase commitment , with the exception of certain fixed costs . in addition , under the ethylene sales agreement , if production costs billed to westlake on an annual basis are less than 95 % of the actual production costs incurred by opco during the contract year , opco is entitled to recover the shortfall in such production costs ( proportionate to the volume sold to westlake ) in the subsequent year ( `` shortfall `` ) . the shortfall is recognized during the period in which the related operating , maintenance or turnaround activities occur . 28 we sell ethylene production in excess of volumes sold to westlake , as well as all associated co-products resulting from the ethylene production , directly to third parties on either a spot or contract basis . net proceeds ( after transportation and other costs ) from the sales of associated co-products that result from the production of ethylene purchased by westlake are netted against the ethylene price charged to westlake under the ethylene sales agreement , thereby substantially reducing our exposure to fluctuations in the market prices of these co-products . during 2016 , all the third-party ethylene and associated co-products sales generated greater than 13 % of our total revenues . the significant drop in crude oil prices since the third quarter of 2014 and continuing through 2016 may create volatility in the north american and global markets , which may result in further reduced prices and margins in third-party ethylene and such co-products sales in 2017. under the services and secondment agreement , opco uses a portion of its production capacity to process purge gas for westlake . on august 4 , 2016 , opco and westlake entered into an amendment to the ethylene sales agreement in order to provide that certain of the pricing components that make up the price for ethylene sold thereunder would be modified to reflect the portion of opco 's production capacity that is used to process westlake 's purge gas instead of producing ethylene and to clarify that costs specific to the processing of westlake 's purge gas would be recovered under the services and secondment agreement , and not the ethylene sales agreement . please refer to note 2 to the consolidated and combined financial statements within this report for more information on the ethylene sales agreement . how we source feedstock in connection with the ipo , opco entered into a 12-year feedstock supply agreement ( the `` feedstock supply agreement `` ) with westlake petrochemicals llc , a wholly owned subsidiary of westlake , under which westlake petrochemicals llc supplies opco with ethane and other feedstocks that opco uses to produce ethylene under the ethylene sales agreement . opco may purchase the ethane and other feedstocks to produce ethylene and resulting co-products to sell to unrelated third parties from westlake petrochemicals llc . please refer to note 2 to the consolidated and combined financial statements within this report for more information on the feedstock supply agreement . how we evaluate operations our management uses a variety of financial and operating metrics to analyze our performance . these metrics are significant factors in assessing our operating results and profitability and include : ( 1 ) production volumes , ( 2 ) operating and maintenance expenses , including turnaround costs , and ( 3 ) mlp distributable cash flow and ebitda . production volumes the amount of profit we generate primarily depends on the volumes of ethylene and resulting co-products we are able to produce at calvert city olefins and lake charles olefins . although westlake has committed to purchasing minimum volumes from us under the ethylene sales agreement , our results of operations are impacted by our ability to : produce sufficient volumes of ethylene to meet our commitments under the ethylene sales agreement or recover our estimated costs through the pricing provisions of the ethylene sales agreement ; contract with third parties for the remaining uncommitted production capacity ; add or increase capacity at our existing production facilities , or add additional production capacity via organic expansion projects and acquisitions ; and achieve or exceed the specified yield factors for natural gas , ethane and other feedstock under the ethylene story_separator_special_tag this increase in interest expense was partially offset by the lower average interest rate for the year ended december 31 , 2016 as compared to the prior year due to the april 2015 repayment of a significant portion of the august 2013 promissory notes ( as defined in `` liquidity and capital resources—indebtedness `` ) , which bear a higher interest rate as compared to our other outstanding debt . 2015 compared with 2014 net sales . net sales decreased by $ 742.5 million , or 42.4 % , to $ 1,007.2 million in 2015 from $ 1,749.7 million in 2014 , primarily due to a lower average sales price of ethylene sold to westlake resulting from the execution of the ethylene sales agreement following the ipo , lower average sales price of ethylene sold to third parties due to the significant decline in market prices in 2015 and a lower volume of ethylene sold to third parties , partially offset by increased volume of ethylene sold to 34 westlake in 2015 as compared to 2014. the total ethylene sales volume in 2015 was lower as compared to 2014 due primarily to westlake 's retention of the predecessor 's ethylene procurement and reselling activities , which was partially offset by higher production in 2015 resulting from the calvert city olefins expansion in 2014 and other efficiency projects . further , co-product sales prices were significantly lower in 2015 as compared to 2014 , primarily due to the significant decline in market prices of coproducts , which resulted in a decrease in co-product sales to third parties . this decrease in sales prices was partially offset by an increase in volume of co-product sales to third parties . additionally , there were no excess feedstock sales subsequent to the ipo in 2014 or in 2015 as such activities were retained by westlake . the overall average sales prices of ethylene and co-products in 2015 decreased by 38.0 % as compared to 2014 and overall sales volumes in 2015 decreased by 4.4 % as compared to 2014. gross profit . gross profit margin percentage decreased to 38.0 % in 2015 from 42.6 % in 2014 primarily due to a reduction in margin for ethylene sold to westlake resulting from the ethylene sales agreement and also due to the decline in margin from ethylene sold to third parties as a result of the significant decline in ethylene market prices during 2015. the decrease was largely offset by a drop in feedstock prices , a decrease in energy costs as well as the absence in 2015 of costs and lost production associated with the calvert city olefins turnaround , conversion and expansion activities that took place during the first and second quarters of 2014. selling , general and administrative expenses . selling , general and administrative expenses decreased by $ 5.7 million , or 19.5 % , to $ 23.6 million in 2015 from $ 29.3 million in 2014. the decrease was mainly attributable to the absence of an allocation from westlake of labor costs attributable to the predecessor 's operations retained by westlake after the ipo , partially offset by incremental selling , general and administrative expenses incurred by the partnership subsequent to the ipo as a result of being a separate publicly-traded partnership . interest expense . interest expense decreased by $ 5.5 million to $ 5.0 million in 2015 from $ 10.5 million in 2014 , primarily due to a lower average interest rate in 2015 as compared to the prior year . the lower average interest rate in 2015 as compared to the prior year was due to the repayment of a significant portion of the august 2013 promissory notes ( as defined in `` liquidity and capital resources—indebtedness `` ) in april 2015 , which bear a higher interest rate as compared to our other outstanding debt . other income , net . other income , net decreased by $ 3.0 million to $ 0.2 million in 2015 from $ 3.2 million in 2014 , primarily due to the absence of income attributable to the predecessor 's equity stake in a natural gas liquids pipeline joint venture that was not contributed to us in connection with the ipo . income taxes . the effective income tax rate was 0.2 % in 2015 as compared to 28.1 % for 2014. the effective income tax rate in 2015 is not comparable to the effective income tax rate for 2014 as the partnership is not subject to federal income taxes subsequent to the ipo . story_separator_special_tag font style= `` font-family : inherit ; font-size:10pt ; `` > the partnership maintains separate bank accounts , but westlake continues to provide treasury services on our behalf under the services and secondment agreement . our sources of liquidity include cash generated from operations , the opco revolver , the mlp revolver and , if necessary and possible under then current market conditions , the issuance of additional equity interests or debt . we believe that cash generated from these sources will be sufficient to meet our short-term working capital requirements and long-term capital expenditure requirements and to make quarterly cash distributions . westlake may also provide other direct and indirect financing to us from time to time , although it is not required to do so . in order to fund non-annual turnaround expenditures , we cause opco to reserve approximately $ 30.0 million during each twelve-month period for turnaround activities . each of opco 's ethylene production facilities requires turnaround maintenance approximately every five years . by reserving additional cash annually , we intend to reduce the variability in opco 's cash flow . westlake 's purchase price for ethylene purchased under the ethylene sales agreement includes a component ( adjusted annually ) designed to cover , over the long term , substantially all of opco 's turnaround expenditures . our cash is generated from cash distributions from opco . opco was a restricted

