our revenue outside of the united states accounted for approximately 27 % , 26 % and 27 % of our consolidated revenue in the years ended december 31 , 2015 , 2014 and 2013 , respectively . we intend to continue to expand our international sales efforts and believe opportunities exist to serve the needs of product developers and engineers in select new geographic regions . we have grown our total revenue from $ 98.9 million in 2011 to $ 264.1 million in 2015. during this period , our operating expenses increased from $ 32.7 million in 2011 to $ 87.3 million in 2015. we have grown our income from operations from $ 26.9 million in 2011 to $ 67.1 million in 2015. our recent growth in revenue and income from operations has been accompanied by increased cost of revenues and operating expenses . we expect to increasingly invest in our operations to support anticipated future growth as discussed more fully below . in addition , we believe that a number of trends affecting our industry have affected our results of operations and may continue to do so . for example , we believe that many of our target product developer and engineer customers have increasing e-commerce expectations , are facing increased pressure to accelerate the time to market for their products and continue to migrate from using 2d cad to using 3d cad for their design needs . we believe we continue to be well positioned to benefit from these trends , given our proprietary technology that enables us to automate and integrate the majority of activities involved in procuring custom parts , starting with our elegant web interface through which a product developer or engineer submits a 3d cad part design . while our business may be positively affected by these trends , our results may also be favorably or unfavorably impacted by other trends that affect product developer and engineer orders for custom parts in low volumes , including , among others , changes in product developer and engineer preferences or needs , developments in our industry and among our competitors , and factors impacting new product development volume such as economic conditions . for a more complete discussion of the risks facing our business , see part 1 item 1a . “ risk factors . ” 32 key financial measures and trends revenue our operations are comprised of three geographic business units in the united states , europe and japan . revenue is derived from our injection molding ( protomold ) , cnc machining ( firstcut ) and 3d printing ( fineline ) product lines . injection molding ( protomold ) revenue consists of sales of custom injection molds and injection-molded parts . cnc machining ( firstcut ) revenue consists of sales of cnc-machined custom parts . 3d printing ( fineline ) revenue consists of sales of 3d-printed parts . our revenue is generated from a diverse customer base , with no single customer company representing more than 2 % of our total revenue in 2015. our historical and current efforts to increase revenue have been directed at gaining new customers and selling to our existing customer base by increasing marketing and selling activities , offering additional product lines such as the introduction of our cnc machining ( firstcut ) product line in 2007 and 3d printing ( fineline ) through our acquisition of fineline prototyping , inc. ( fineline ) in 2014 , expanding internationally such as the opening of our japanese office in 2009 and through our acquisition of alphaform in october 2015 , improving the usability of our product lines such as our web-centric applications , and expanding the breadth and scope of our products such as by adding more sizes and materials to our offerings . during 2015 , we served 27,235 unique product developers and engineers , an increase of 26 % over the same period in 2014. of those product developers and engineers served in 2015 , 13,504 were existing product developers and engineers who had ordered from us in the past , an increase of 37 % over the comparable period in 2014 , and 13,731 were new product developers and engineers who ordered from us for the first time in 2015 , an increase of 17 % over the comparable period in 2014. during 2014 , we served 21,552 unique product developers and engineers , an increase of 34 % over the same period in 2013. of those product developers and engineers served in 2014 , 9,839 were existing product developers and engineers who had ordered from us in the past , an increase of 26 % over the comparable period in 2013 , and 11,713 were new product developers and engineers who ordered from us for the first time in 2014 , an increase of 41 % over the comparable period in 2013. we experienced strong growth in the number of unique product developers and engineers served in 2014 , partially as a result of our acquisition of fineline in april , 2014. during 2013 , we served 16,128 unique product developers and engineers , an increase of 20 % over the same period in 2012. of those product developers and engineers served in 2013 , 7,826 were existing product developers and engineers who had ordered from us in the past , an increase of 30 % over the comparable period in 2012 , and 8,302 new product developers and engineers who ordered from us for the first time in 2013 , an increase of 12 % over the comparable period in 2012. cost of revenue , gross profit and gross margin cost of revenue consists primarily of raw materials , equipment depreciation , employee compensation , benefits , stock-based compensation , facilities costs and overhead allocations associated with the manufacturing process for molds and custom parts . story_separator_special_tag if these funds are needed for our domestic operations , we would be required to accrue and pay u.s. taxes to repatriate these funds . however , our intent is to permanently reinvest these funds outside the u.s. and our current plans do not demonstrate a need to repatriate them to fund our domestic operations . we believe that our existing cash and cash equivalents together with cash generated from operations will be sufficient to meet our working capital expenditure requirements for at least the next 12 months . story_separator_special_tag convertible debt securities may result in dilution to our shareholders . if we raise additional funds through the issuance of convertible debt securities or enter into credit facilities , these securities and debt holders could have rights senior to those of our common stock , and this debt could contain covenants that would restrict our operations . we may require additional capital beyond our currently forecasted amounts . any such required additional capital may not be available on terms acceptable to us , or at all . our future capital requirements will depend on many factors , including the following : the revenue growth in injection molding ( protomold ) , cnc machining ( firstcut ) and 3d printing ( fineline ) product lines ; costs of operations , including costs relating to expansion and growth ; the emergence of competing or complementary technological developments ; the costs of filing , prosecuting , defending and enforcing any patent claims and other intellectual product rights , or participating in litigation-related activities ; and the acquisition of businesses , products and technologies , although we currently have no commitments or agreements relating to any of these types of transactions . our annual capital expenditures generally have varied between approximately 8 % and 19 % of annual revenue . we believe future growth capital expenditures , excluding any expenditures for buildings and maintenance capital we might purchase for our operations , are likely to vary between approximately 8 % and 12 % of annual revenue . contractual obligations as of december 31 , 2015 , our contractual obligations and the effect such obligations are expected to have on our liquidity and cash flows in future periods were as follows : replace_table_token_14_th 41 the table above reflects only payment obligations that are fixed and determinable . our commitments for operating leases relate to three of our united states manufacturing facilities , our european sales , customer service and technical support offices , three alphaform manufacturing and office facilities located in germany and finland and our japan facility . subsequent to the acquisition of alphaform , we entered into lease agreements for facilities located in germany and finland as referenced above . these obligations are included in the table above . financing arrangements the following table summarizes our financing arrangements as of december 31 , 2015 and 2014 : replace_table_token_15_th inflation we believe that inflation and changing prices have not had a material effect on our financial condition during the three most recent fiscal years . off-balance sheet arrangements since our inception , we have not engaged in any off-balance sheet arrangements , including the use of structured finance , special purpose entities or variable interest entities . critical accounting policies and use of estimates the discussion and analysis of our financial condition and results of operations is based upon our consolidated financial statements , which have been prepared in accordance with accounting principles generally accepted in the united states . the preparation of these financial statements requires us to make estimates , judgments and assumptions that affect the reported amount of assets , liabilities , revenue , expenses and related disclosures . on an ongoing basis , we evaluate our estimates , including those related to revenue recognition , goodwill , other intangible assets , stock-based compensation , and income taxes . we base our estimates of the carrying value of certain assets and liabilities on historical experience and on various other assumptions that we believe to be reasonable under the circumstances . in many cases , we could reasonably have used different accounting policies and estimates . in some cases , changes in the accounting estimates are reasonably likely to occur from period to period . management has discussed the development , selection and disclosure of these estimates with the audit committee of our board of directors . our actual results may differ significantly from these estimates under different assumptions or conditions . we believe the following critical accounting policies affect our more significant judgments used in the preparation of our consolidated financial statements . see the notes to consolidated financial statements included in item 8 . “ financial statements and supplementary data ” in this annual report on form 10-k for additional information about these critical accounting policies , as well as a description of our other accounting policies . 42 revenue recognition we recognize revenue in accordance with asc 605 , revenue recognition , which states that revenue is realized or realizable and earned when all of the following criteria are met : ( 1 ) persuasive evidence of an arrangement exists , ( 2 ) delivery has occurred or services have been rendered , ( 3 ) the price to the buyer is fixed or determinable , and ( 4 ) collectability is reasonably assured . revenue is recognized upon transfer of title and risk of loss , which is generally upon the shipment of parts in our injection molding ( protomold ) , cnc machining ( firstcut ) , 3d printing ( fineline ) and other product lines . goodwill we recognize goodwill in accordance with asc 350 , intangibles — goodwill and other . goodwill is the excess of cost of an acquired entity over the amounts assigned to assets acquired and liabilities assumed in a business combination . goodwill is not amortized . goodwill is tested for impairment annually in the fourth quarter of each year ,

cash flows from operating activities cash flow from operating activities during 2015 primarily consisted of net income of $ 46.5 million , adjusted for certain non-cash items , including depreciation and amortization of $ 14.1 million and stock-based compensation expense of $ 6.1 million , partially offset by excess tax benefit from stock-based compensation expense of $ 5.5 million . the cash flow from operating activities during 2015 compared to 2014 increased $ 1.3 million due to increases in net income of $ 4.9 million , depreciation and amortization of $ 3.0 million , deferred taxes of $ 4.7 million and stock-based compensation expense of $ 1.3 million , which were partially offset by a gain on acquisition of $ 0.3 million , an increase in excess tax benefit from stock-based compensation of $ 1.1 million , and decreases in amortization of held-to-maturity securities of $ 0.3 million and changes in operating assets and liabilities of $ 10.9 million . cash flow from operating activities during 2014 primarily consisted of net income of $ 41.6 million , adjusted for certain non-cash items , including depreciation and amortization of $ 11.1 million and stock-based compensation expense of $ 4.8 million , partially offset by excess tax benefit from stock-based compensation expense of $ 4.5 million .


 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 from operating activities cash flow from operating activities during 2015 primarily consisted of net income of $ 46.5 million , adjusted for certain non-cash items , including depreciation and amortization of $ 14.1 million and stock-based compensation expense of $ 6.1 million , partially offset by excess tax benefit from stock-based compensation expense of $ 5.5 million . the cash flow from operating activities during 2015 compared to 2014 increased $ 1.3 million due to increases in net income of $ 4.9 million , depreciation and amortization of $ 3.0 million , deferred taxes of $ 4.7 million and stock-based compensation expense of $ 1.3 million , which were partially offset by a gain on acquisition of $ 0.3 million , an increase in excess tax benefit from stock-based compensation of $ 1.1 million , and decreases in amortization of held-to-maturity securities of $ 0.3 million and changes in operating assets and liabilities of $ 10.9 million . cash flow from operating activities during 2014 primarily consisted of net income of $ 41.6 million , adjusted for certain non-cash items , including depreciation and amortization of $ 11.1 million and stock-based compensation expense of $ 4.8 million , partially offset by excess tax benefit from stock-based compensation expense of $ 4.5 million .
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 Suspicious Activity Report : our revenue outside of the united states accounted for approximately 27 % , 26 % and 27 % of our consolidated revenue in the years ended december 31 , 2015 , 2014 and 2013 , respectively . we intend to continue to expand our international sales efforts and believe opportunities exist to serve the needs of product developers and engineers in select new geographic regions . we have grown our total revenue from $ 98.9 million in 2011 to $ 264.1 million in 2015. during this period , our operating expenses increased from $ 32.7 million in 2011 to $ 87.3 million in 2015. we have grown our income from operations from $ 26.9 million in 2011 to $ 67.1 million in 2015. our recent growth in revenue and income from operations has been accompanied by increased cost of revenues and operating expenses . we expect to increasingly invest in our operations to support anticipated future growth as discussed more fully below . in addition , we believe that a number of trends affecting our industry have affected our results of operations and may continue to do so . for example , we believe that many of our target product developer and engineer customers have increasing e-commerce expectations , are facing increased pressure to accelerate the time to market for their products and continue to migrate from using 2d cad to using 3d cad for their design needs . we believe we continue to be well positioned to benefit from these trends , given our proprietary technology that enables us to automate and integrate the majority of activities involved in procuring custom parts , starting with our elegant web interface through which a product developer or engineer submits a 3d cad part design . while our business may be positively affected by these trends , our results may also be favorably or unfavorably impacted by other trends that affect product developer and engineer orders for custom parts in low volumes , including , among others , changes in product developer and engineer preferences or needs , developments in our industry and among our competitors , and factors impacting new product development volume such as economic conditions . for a more complete discussion of the risks facing our business , see part 1 item 1a . “ risk factors . ” 32 key financial measures and trends revenue our operations are comprised of three geographic business units in the united states , europe and japan . revenue is derived from our injection molding ( protomold ) , cnc machining ( firstcut ) and 3d printing ( fineline ) product lines . injection molding ( protomold ) revenue consists of sales of custom injection molds and injection-molded parts . cnc machining ( firstcut ) revenue consists of sales of cnc-machined custom parts . 3d printing ( fineline ) revenue consists of sales of 3d-printed parts . our revenue is generated from a diverse customer base , with no single customer company representing more than 2 % of our total revenue in 2015. our historical and current efforts to increase revenue have been directed at gaining new customers and selling to our existing customer base by increasing marketing and selling activities , offering additional product lines such as the introduction of our cnc machining ( firstcut ) product line in 2007 and 3d printing ( fineline ) through our acquisition of fineline prototyping , inc. ( fineline ) in 2014 , expanding internationally such as the opening of our japanese office in 2009 and through our acquisition of alphaform in october 2015 , improving the usability of our product lines such as our web-centric applications , and expanding the breadth and scope of our products such as by adding more sizes and materials to our offerings . during 2015 , we served 27,235 unique product developers and engineers , an increase of 26 % over the same period in 2014. of those product developers and engineers served in 2015 , 13,504 were existing product developers and engineers who had ordered from us in the past , an increase of 37 % over the comparable period in 2014 , and 13,731 were new product developers and engineers who ordered from us for the first time in 2015 , an increase of 17 % over the comparable period in 2014. during 2014 , we served 21,552 unique product developers and engineers , an increase of 34 % over the same period in 2013. of those product developers and engineers served in 2014 , 9,839 were existing product developers and engineers who had ordered from us in the past , an increase of 26 % over the comparable period in 2013 , and 11,713 were new product developers and engineers who ordered from us for the first time in 2014 , an increase of 41 % over the comparable period in 2013. we experienced strong growth in the number of unique product developers and engineers served in 2014 , partially as a result of our acquisition of fineline in april , 2014. during 2013 , we served 16,128 unique product developers and engineers , an increase of 20 % over the same period in 2012. of those product developers and engineers served in 2013 , 7,826 were existing product developers and engineers who had ordered from us in the past , an increase of 30 % over the comparable period in 2012 , and 8,302 new product developers and engineers who ordered from us for the first time in 2013 , an increase of 12 % over the comparable period in 2012. cost of revenue , gross profit and gross margin cost of revenue consists primarily of raw materials , equipment depreciation , employee compensation , benefits , stock-based compensation , facilities costs and overhead allocations associated with the manufacturing process for molds and custom parts . story_separator_special_tag if these funds are needed for our domestic operations , we would be required to accrue and pay u.s. taxes to repatriate these funds . however , our intent is to permanently reinvest these funds outside the u.s. and our current plans do not demonstrate a need to repatriate them to fund our domestic operations . we believe that our existing cash and cash equivalents together with cash generated from operations will be sufficient to meet our working capital expenditure requirements for at least the next 12 months . story_separator_special_tag convertible debt securities may result in dilution to our shareholders . if we raise additional funds through the issuance of convertible debt securities or enter into credit facilities , these securities and debt holders could have rights senior to those of our common stock , and this debt could contain covenants that would restrict our operations . we may require additional capital beyond our currently forecasted amounts . any such required additional capital may not be available on terms acceptable to us , or at all . our future capital requirements will depend on many factors , including the following : the revenue growth in injection molding ( protomold ) , cnc machining ( firstcut ) and 3d printing ( fineline ) product lines ; costs of operations , including costs relating to expansion and growth ; the emergence of competing or complementary technological developments ; the costs of filing , prosecuting , defending and enforcing any patent claims and other intellectual product rights , or participating in litigation-related activities ; and the acquisition of businesses , products and technologies , although we currently have no commitments or agreements relating to any of these types of transactions . our annual capital expenditures generally have varied between approximately 8 % and 19 % of annual revenue . we believe future growth capital expenditures , excluding any expenditures for buildings and maintenance capital we might purchase for our operations , are likely to vary between approximately 8 % and 12 % of annual revenue . contractual obligations as of december 31 , 2015 , our contractual obligations and the effect such obligations are expected to have on our liquidity and cash flows in future periods were as follows : replace_table_token_14_th 41 the table above reflects only payment obligations that are fixed and determinable . our commitments for operating leases relate to three of our united states manufacturing facilities , our european sales , customer service and technical support offices , three alphaform manufacturing and office facilities located in germany and finland and our japan facility . subsequent to the acquisition of alphaform , we entered into lease agreements for facilities located in germany and finland as referenced above . these obligations are included in the table above . financing arrangements the following table summarizes our financing arrangements as of december 31 , 2015 and 2014 : replace_table_token_15_th inflation we believe that inflation and changing prices have not had a material effect on our financial condition during the three most recent fiscal years . off-balance sheet arrangements since our inception , we have not engaged in any off-balance sheet arrangements , including the use of structured finance , special purpose entities or variable interest entities . critical accounting policies and use of estimates the discussion and analysis of our financial condition and results of operations is based upon our consolidated financial statements , which have been prepared in accordance with accounting principles generally accepted in the united states . the preparation of these financial statements requires us to make estimates , judgments and assumptions that affect the reported amount of assets , liabilities , revenue , expenses and related disclosures . on an ongoing basis , we evaluate our estimates , including those related to revenue recognition , goodwill , other intangible assets , stock-based compensation , and income taxes . we base our estimates of the carrying value of certain assets and liabilities on historical experience and on various other assumptions that we believe to be reasonable under the circumstances . in many cases , we could reasonably have used different accounting policies and estimates . in some cases , changes in the accounting estimates are reasonably likely to occur from period to period . management has discussed the development , selection and disclosure of these estimates with the audit committee of our board of directors . our actual results may differ significantly from these estimates under different assumptions or conditions . we believe the following critical accounting policies affect our more significant judgments used in the preparation of our consolidated financial statements . see the notes to consolidated financial statements included in item 8 . “ financial statements and supplementary data ” in this annual report on form 10-k for additional information about these critical accounting policies , as well as a description of our other accounting policies . 42 revenue recognition we recognize revenue in accordance with asc 605 , revenue recognition , which states that revenue is realized or realizable and earned when all of the following criteria are met : ( 1 ) persuasive evidence of an arrangement exists , ( 2 ) delivery has occurred or services have been rendered , ( 3 ) the price to the buyer is fixed or determinable , and ( 4 ) collectability is reasonably assured . revenue is recognized upon transfer of title and risk of loss , which is generally upon the shipment of parts in our injection molding ( protomold ) , cnc machining ( firstcut ) , 3d printing ( fineline ) and other product lines . goodwill we recognize goodwill in accordance with asc 350 , intangibles — goodwill and other . goodwill is the excess of cost of an acquired entity over the amounts assigned to assets acquired and liabilities assumed in a business combination . goodwill is not amortized . goodwill is tested for impairment annually in the fourth quarter of each year ,

