the length of stay requirements were suspended in order to facilitate the transfer of patients from general acute care hospitals and expand hospital bed capacity to care for covid-19 patients ( see “ regulatory changes ” for further discussion of the temporary suspension of regulations ) . during the year ended december 31 , 2020 , we played a critical role in caring for patients during the covid-19 pandemic due , in part , to our rapid preparation and implementation of modifications that supported the treatment of covid-19 patients . the following table shows revenue , patient days , and occupancy rates for each of the periods presented , as well as the number of critical illness recovery hospitals we owned at the end of each period . replace_table_token_8_th _ ( 1 ) represents the number of hospitals owned at the end of each period presented . 52 rehabilitation hospital segment . our rehabilitation hospitals receive most of their admissions from general acute care hospitals . beginning in march 2020 , a number of waivers and modifications of certain requirements under the medicare , medicaid and chip programs were authorized , including certain regulations governing admissions into rehabilitation hospitals . this was done in order to facilitate the transfer of patients from general acute care hospitals and critical illness recovery hospitals and to expand hospital bed capacity to care for covid-19 patients ( see “ regulatory changes ” for further discussion of the temporary suspension of regulations ) . our rehabilitation hospitals were affected by the suspension of elective surgeries at hospitals and other facilities at the beginning of the pandemic , which resulted in reduced need for inpatient rehabilitation services . beginning in may 2020 , state governments and health departments began to ease restrictions and hospitals began to perform elective surgeries again , which has increased the need for the services provided by our rehabilitation hospitals . the following table shows revenue , patient days , and occupancy rates for each of the periods presented , as well as the number of rehabilitation hospitals we owned at the end of each period . replace_table_token_9_th _ ( 1 ) represents the number of hospitals owned at the end of each period presented . 53 outpatient rehabilitation segment . beginning in mid-march 2020 , state governments began implementing mandatory closures of non-essential or non-life sustaining businesses , restricting travel and individual activities outside of the home , closing schools , and mandating other social distancing measures . additionally , hospitals and other facilities began to suspend elective surgeries . as a result , our outpatient rehabilitation clinics experienced significantly less patient visit volume due to a decline in patient referrals from physicians , a reduction in workers ' compensation injury visits resulting from the temporary closure of businesses , and the suspension of elective surgeries which would have required outpatient rehabilitation services . beginning in may 2020 , state governments began to ease restrictions imposed on businesses and individuals , physician offices began reopening for routine office visits , and hospitals and other facilities began performing elective surgeries again , which resulted in an increased need for the services provided by our outpatient rehabilitation clinics . the following table shows revenue and patient visits for each of the periods presented , as well as the number of working days for each period . replace_table_token_10_th _ ( 1 ) represents the number of days in which normal business operations were conducted during the periods presented . 54 concentra segment . beginning in mid-march 2020 , state governments began placing significant restrictions on businesses and mandating closures of non-essential or non-life sustaining businesses , causing many employers to furlough their workforce and temporarily cease or significantly reduce their operations . these actions had significant effects on our patient visit volumes . beginning in may 2020 , state governments began to ease restrictions imposed on businesses and employers began to increase their workforce , which resulted in an increased need for our occupational health services . during the year ended december 31 , 2020 , concentra expanded its services to provide covid-19 screening and testing at its centers and various onsite clinics located at employer worksites . the following table shows revenue and patient visits for each of the periods presented , as well as the number of working days for each period . replace_table_token_11_th _ ( 1 ) represents the number of days in which normal business operations were conducted during the periods presented . please refer to “ summary financial results ” and “ results of operations ” for further discussion of our segment performance measures . please refer to “ operating statistics ” for further discussion regarding the uses and calculations of the metrics provided above . 55 summary financial results year ended december 31 , 2020 for the year ended december 31 , 2020 , our revenue increased 1.4 % to $ 5,531.7 million , compared to $ 5,453.9 million for the year ended december 31 , 2019. income from operations increased 20.3 % to $ 567.7 million for the year ended december 31 , 2020 , compared to $ 471.9 million for the year ended december 31 , 2019. for the year ended december 31 , 2020 , income from operations included other operating income of $ 90.0 million related to the recognition of payments received under the public health and social services emergency fund , also referred to as the provider relief fund , for health care related expenses and loss of revenue attributable to the covid-19 pandemic . refer to note 22 – cares act of the notes to our consolidated financial statements included herein for further information . story_separator_special_tag however , the cares act waives the site neutral payment rate for patients admitted during the covid-19 emergency period and in response to the public health emergency , as discussed above . fiscal year 2021. on september 18 , 2020 , cms published the final rule updating policies and payment rates for the ltch-pps for fiscal year 2021 ( affecting discharges and cost reporting periods beginning on or after october 1 , 2020 through september 30 , 2021 ) . certain errors in the final rule were corrected in a document published december 7 , 2020. the standard federal rate was set at $ 43,755 , an increase from the standard federal rate applicable during fiscal year 2020 of $ 42,678. the update to the standard federal rate for fiscal year 2021 included a market basket increase of 2.3 % with no productivity adjustment . the standard federal rate also included an area wage budget neutrality factor of 1.0016837 and a permanent , one-time budget neutrality adjustment of 1.000517 in connection with the elimination of the 25 percent rule . as a result of the cares act , all ltch cases are paid at the standard federal rate during the public health emergency . if the public health emergency ends during fiscal year 2021 , then cms will return to using the site-neutral payment rate for reimbursement of cases that do not meet the ltch patient criteria . the fixed-loss amount for high cost outlier cases paid under ltch-pps was set at $ 27,195 , an increase from the fixed-loss amount in the 2020 fiscal year of $ 26,778. the fixed-loss amount for high cost outlier cases paid under the site-neutral payment rate was set at $ 29,064 , an increase from the fixed-loss amount in the 2020 fiscal year of $ 26,552. medicare reimbursement of irf services the following is a summary of significant regulatory changes to the medicare prospective payment system for our rehabilitation hospitals , which are certified by medicare as irfs , which have affected our results of operations , as well as the policies and payment rates that may affect our future results of operations . medicare payments to our rehabilitation hospitals are made in accordance with irf-pps . fiscal year 2019 . on august 6 , 2018 , cms published the final rule updating policies and payment rates for the irf-pps for fiscal year 2019 ( affecting discharges and cost reporting periods beginning on or after october 1 , 2018 through september 30 , 2019 ) . the standard payment conversion factor for discharges for fiscal year 2019 was set at $ 16,021 , an increase from the standard payment conversion factor applicable during fiscal year 2018 of $ 15,838. the update to the standard payment conversion factor for fiscal year 2019 included a market basket increase of 2.9 % , less a productivity adjustment of 0.8 % , and less a reduction of 0.75 % mandated by the aca . cms increased the outlier threshold amount for fiscal year 2019 to $ 9,402 from $ 8,679 established in the final rule for fiscal year 2018 . 61 fiscal year 2020. on august 8 , 2019 , cms published the final rule updating policies and payment rates for the irf-pps for fiscal year 2020 ( affecting discharges and cost reporting periods beginning on or after october 1 , 2019 through september 30 , 2020 ) . the standard payment conversion factor for discharges for fiscal year 2020 was set at $ 16,489 , an increase from the standard payment conversion factor applicable during fiscal year 2019 of $ 16,021. the update to the standard payment conversion factor for fiscal year 2020 included a market basket increase of 2.9 % , less a productivity adjustment of 0.4 % . cms decreased the outlier threshold amount for fiscal year 2020 to $ 9,300 from $ 9,402 established in the final rule for fiscal year 2019. fiscal year 2021. on august 10 , 2020 , cms published the final rule updating policies and payment rates for the irf-pps for fiscal year 2021 ( affecting discharges and cost reporting periods beginning on or after october 1 , 2020 through september 30 , 2021 ) . the standard payment conversion factor for discharges for fiscal year 2021 was set at $ 16,856 , an increase from the standard payment conversion factor applicable during fiscal year 2020 of $ 16,489. the update to the standard payment conversion factor for fiscal year 2021 included a market basket increase of 2.4 % with no productivity adjustment . cms decreased the outlier threshold amount for fiscal year 2021 to $ 7,906 from $ 9,300 established in the final rule for fiscal year 2020. medicare reimbursement of outpatient rehabilitation clinic services outpatient rehabilitation providers enroll in medicare as a rehabilitation agency , a clinic , or a public health agency . the medicare program reimburses outpatient rehabilitation providers based on the medicare physician fee schedule . for services provided in 2017 through 2019 , a 0.5 % update was applied each year to the fee schedule payment rates , subject to an adjustment beginning in 2019 under the mips . in 2019 , cms added physical and occupational therapists to the list of mips eligible clinicians . for these therapists in private practice , payments under the fee schedule are subject to adjustment in a later year based on their performance in mips according to established performance standards . calendar year 2021 is the first year that payments are adjusted , based upon t he therapist 's performance under mips in 2019. providers in facility-based outpatient therapy settings are excluded from mips eligibility and therefore not subject to this payment adjustment . for services provided in 2020 through 2025 , a 0.0 % percent update will be applied each year to the fee schedule payment rates , subject to adjustments under mips and the apms . in 2026 and subsequent years , eligible professionals

liquidity and capital resources cash flows for the years ended december 31 , 2018 , 2019 , and 2020 in the following , we discuss cash flows from operating activities , investing activities , and financing activities . replace_table_token_22_th operating activities provided $ 1,028.1 million of cash flows for the year ended december 31 , 2020 , compared to $ 445.2 million of cash flows for the year ended december 31 , 2019. the increase in cash flows provided by operating activities is primarily attributable to $ 318.1 million of advanced payments received under the accelerated and advance payment program , as well as $ 172.6 million of payments received under the provider relief fund . refer to note 22 – cares act of the notes to our consolidated financial statements included herein for further information . our days sales outstanding was 56 days at december 31 , 2020 , while our days sales outstanding was 51 days at both december 31 , 2019 and 2018. our days sales outstanding will fluctuate based upon variability in our collection cycles and patient volumes . for the year ended december 31 , 2020 , our days sales outstanding was primarily impacted by an increase in our medicare receivables at our hospitals . operating activities provided $ 445.2 million of cash flows for the year ended december 31 , 2019 , compared to $ 494.2 million of cash flows for the year ended december 31 , 2018. the lower operating cash flows were principally driven by the change in our accounts receivable .


 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.
     ```liquidity and capital resources cash flows for the years ended december 31 , 2018 , 2019 , and 2020 in the following , we discuss cash flows from operating activities , investing activities , and financing activities . replace_table_token_22_th operating activities provided $ 1,028.1 million of cash flows for the year ended december 31 , 2020 , compared to $ 445.2 million of cash flows for the year ended december 31 , 2019. the increase in cash flows provided by operating activities is primarily attributable to $ 318.1 million of advanced payments received under the accelerated and advance payment program , as well as $ 172.6 million of payments received under the provider relief fund . refer to note 22 – cares act of the notes to our consolidated financial statements included herein for further information . our days sales outstanding was 56 days at december 31 , 2020 , while our days sales outstanding was 51 days at both december 31 , 2019 and 2018. our days sales outstanding will fluctuate based upon variability in our collection cycles and patient volumes . for the year ended december 31 , 2020 , our days sales outstanding was primarily impacted by an increase in our medicare receivables at our hospitals . operating activities provided $ 445.2 million of cash flows for the year ended december 31 , 2019 , compared to $ 494.2 million of cash flows for the year ended december 31 , 2018. the lower operating cash flows were principally driven by the change in our accounts receivable .
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 Suspicious Activity Report : the length of stay requirements were suspended in order to facilitate the transfer of patients from general acute care hospitals and expand hospital bed capacity to care for covid-19 patients ( see “ regulatory changes ” for further discussion of the temporary suspension of regulations ) . during the year ended december 31 , 2020 , we played a critical role in caring for patients during the covid-19 pandemic due , in part , to our rapid preparation and implementation of modifications that supported the treatment of covid-19 patients . the following table shows revenue , patient days , and occupancy rates for each of the periods presented , as well as the number of critical illness recovery hospitals we owned at the end of each period . replace_table_token_8_th _ ( 1 ) represents the number of hospitals owned at the end of each period presented . 52 rehabilitation hospital segment . our rehabilitation hospitals receive most of their admissions from general acute care hospitals . beginning in march 2020 , a number of waivers and modifications of certain requirements under the medicare , medicaid and chip programs were authorized , including certain regulations governing admissions into rehabilitation hospitals . this was done in order to facilitate the transfer of patients from general acute care hospitals and critical illness recovery hospitals and to expand hospital bed capacity to care for covid-19 patients ( see “ regulatory changes ” for further discussion of the temporary suspension of regulations ) . our rehabilitation hospitals were affected by the suspension of elective surgeries at hospitals and other facilities at the beginning of the pandemic , which resulted in reduced need for inpatient rehabilitation services . beginning in may 2020 , state governments and health departments began to ease restrictions and hospitals began to perform elective surgeries again , which has increased the need for the services provided by our rehabilitation hospitals . the following table shows revenue , patient days , and occupancy rates for each of the periods presented , as well as the number of rehabilitation hospitals we owned at the end of each period . replace_table_token_9_th _ ( 1 ) represents the number of hospitals owned at the end of each period presented . 53 outpatient rehabilitation segment . beginning in mid-march 2020 , state governments began implementing mandatory closures of non-essential or non-life sustaining businesses , restricting travel and individual activities outside of the home , closing schools , and mandating other social distancing measures . additionally , hospitals and other facilities began to suspend elective surgeries . as a result , our outpatient rehabilitation clinics experienced significantly less patient visit volume due to a decline in patient referrals from physicians , a reduction in workers ' compensation injury visits resulting from the temporary closure of businesses , and the suspension of elective surgeries which would have required outpatient rehabilitation services . beginning in may 2020 , state governments began to ease restrictions imposed on businesses and individuals , physician offices began reopening for routine office visits , and hospitals and other facilities began performing elective surgeries again , which resulted in an increased need for the services provided by our outpatient rehabilitation clinics . the following table shows revenue and patient visits for each of the periods presented , as well as the number of working days for each period . replace_table_token_10_th _ ( 1 ) represents the number of days in which normal business operations were conducted during the periods presented . 54 concentra segment . beginning in mid-march 2020 , state governments began placing significant restrictions on businesses and mandating closures of non-essential or non-life sustaining businesses , causing many employers to furlough their workforce and temporarily cease or significantly reduce their operations . these actions had significant effects on our patient visit volumes . beginning in may 2020 , state governments began to ease restrictions imposed on businesses and employers began to increase their workforce , which resulted in an increased need for our occupational health services . during the year ended december 31 , 2020 , concentra expanded its services to provide covid-19 screening and testing at its centers and various onsite clinics located at employer worksites . the following table shows revenue and patient visits for each of the periods presented , as well as the number of working days for each period . replace_table_token_11_th _ ( 1 ) represents the number of days in which normal business operations were conducted during the periods presented . please refer to “ summary financial results ” and “ results of operations ” for further discussion of our segment performance measures . please refer to “ operating statistics ” for further discussion regarding the uses and calculations of the metrics provided above . 55 summary financial results year ended december 31 , 2020 for the year ended december 31 , 2020 , our revenue increased 1.4 % to $ 5,531.7 million , compared to $ 5,453.9 million for the year ended december 31 , 2019. income from operations increased 20.3 % to $ 567.7 million for the year ended december 31 , 2020 , compared to $ 471.9 million for the year ended december 31 , 2019. for the year ended december 31 , 2020 , income from operations included other operating income of $ 90.0 million related to the recognition of payments received under the public health and social services emergency fund , also referred to as the provider relief fund , for health care related expenses and loss of revenue attributable to the covid-19 pandemic . refer to note 22 – cares act of the notes to our consolidated financial statements included herein for further information . story_separator_special_tag however , the cares act waives the site neutral payment rate for patients admitted during the covid-19 emergency period and in response to the public health emergency , as discussed above . fiscal year 2021. on september 18 , 2020 , cms published the final rule updating policies and payment rates for the ltch-pps for fiscal year 2021 ( affecting discharges and cost reporting periods beginning on or after october 1 , 2020 through september 30 , 2021 ) . certain errors in the final rule were corrected in a document published december 7 , 2020. the standard federal rate was set at $ 43,755 , an increase from the standard federal rate applicable during fiscal year 2020 of $ 42,678. the update to the standard federal rate for fiscal year 2021 included a market basket increase of 2.3 % with no productivity adjustment . the standard federal rate also included an area wage budget neutrality factor of 1.0016837 and a permanent , one-time budget neutrality adjustment of 1.000517 in connection with the elimination of the 25 percent rule . as a result of the cares act , all ltch cases are paid at the standard federal rate during the public health emergency . if the public health emergency ends during fiscal year 2021 , then cms will return to using the site-neutral payment rate for reimbursement of cases that do not meet the ltch patient criteria . the fixed-loss amount for high cost outlier cases paid under ltch-pps was set at $ 27,195 , an increase from the fixed-loss amount in the 2020 fiscal year of $ 26,778. the fixed-loss amount for high cost outlier cases paid under the site-neutral payment rate was set at $ 29,064 , an increase from the fixed-loss amount in the 2020 fiscal year of $ 26,552. medicare reimbursement of irf services the following is a summary of significant regulatory changes to the medicare prospective payment system for our rehabilitation hospitals , which are certified by medicare as irfs , which have affected our results of operations , as well as the policies and payment rates that may affect our future results of operations . medicare payments to our rehabilitation hospitals are made in accordance with irf-pps . fiscal year 2019 . on august 6 , 2018 , cms published the final rule updating policies and payment rates for the irf-pps for fiscal year 2019 ( affecting discharges and cost reporting periods beginning on or after october 1 , 2018 through september 30 , 2019 ) . the standard payment conversion factor for discharges for fiscal year 2019 was set at $ 16,021 , an increase from the standard payment conversion factor applicable during fiscal year 2018 of $ 15,838. the update to the standard payment conversion factor for fiscal year 2019 included a market basket increase of 2.9 % , less a productivity adjustment of 0.8 % , and less a reduction of 0.75 % mandated by the aca . cms increased the outlier threshold amount for fiscal year 2019 to $ 9,402 from $ 8,679 established in the final rule for fiscal year 2018 . 61 fiscal year 2020. on august 8 , 2019 , cms published the final rule updating policies and payment rates for the irf-pps for fiscal year 2020 ( affecting discharges and cost reporting periods beginning on or after october 1 , 2019 through september 30 , 2020 ) . the standard payment conversion factor for discharges for fiscal year 2020 was set at $ 16,489 , an increase from the standard payment conversion factor applicable during fiscal year 2019 of $ 16,021. the update to the standard payment conversion factor for fiscal year 2020 included a market basket increase of 2.9 % , less a productivity adjustment of 0.4 % . cms decreased the outlier threshold amount for fiscal year 2020 to $ 9,300 from $ 9,402 established in the final rule for fiscal year 2019. fiscal year 2021. on august 10 , 2020 , cms published the final rule updating policies and payment rates for the irf-pps for fiscal year 2021 ( affecting discharges and cost reporting periods beginning on or after october 1 , 2020 through september 30 , 2021 ) . the standard payment conversion factor for discharges for fiscal year 2021 was set at $ 16,856 , an increase from the standard payment conversion factor applicable during fiscal year 2020 of $ 16,489. the update to the standard payment conversion factor for fiscal year 2021 included a market basket increase of 2.4 % with no productivity adjustment . cms decreased the outlier threshold amount for fiscal year 2021 to $ 7,906 from $ 9,300 established in the final rule for fiscal year 2020. medicare reimbursement of outpatient rehabilitation clinic services outpatient rehabilitation providers enroll in medicare as a rehabilitation agency , a clinic , or a public health agency . the medicare program reimburses outpatient rehabilitation providers based on the medicare physician fee schedule . for services provided in 2017 through 2019 , a 0.5 % update was applied each year to the fee schedule payment rates , subject to an adjustment beginning in 2019 under the mips . in 2019 , cms added physical and occupational therapists to the list of mips eligible clinicians . for these therapists in private practice , payments under the fee schedule are subject to adjustment in a later year based on their performance in mips according to established performance standards . calendar year 2021 is the first year that payments are adjusted , based upon t he therapist 's performance under mips in 2019. providers in facility-based outpatient therapy settings are excluded from mips eligibility and therefore not subject to this payment adjustment . for services provided in 2020 through 2025 , a 0.0 % percent update will be applied each year to the fee schedule payment rates , subject to adjustments under mips and the apms . in 2026 and subsequent years , eligible professionals

