2012 ppg annual report and form 10-k 27 operations in 2011 compared to 2010 , but the increase was reduced by cash used to fund an increase in working capital of $ 212 million driven by our sales growth in 2011 . operating working capital is a subset of total working capital and represents ( 1 ) trade receivables-net of the allowance for doubtful accounts , plus ( 2 ) inventories on a first- in , first-out ( 201cfifo 201d ) basis , less ( 3 ) trade creditors 2019 liabilities . see note 3 , 201cworking capital detail 201d under item 8 of this form 10-k for further information related to the components of the company 2019s operating working capital . we believe operating working capital represents the key components of working capital under the operating control of our businesses . operating working capital at december 31 , 2012 and 2011 was $ 2.9 billion and $ 2.7 billion , respectively . a key metric we use to measure our working capital management is operating working capital as a percentage of sales ( fourth quarter sales annualized ) . .
what are cumulative three year dividends in millions?
operating working capital at december 31 , 2012 increased $ 139 million compared with the prior year end level ; however , excluding the impact of currency and acquisitions , the change was a decrease of $ 21 million during the year ended december 31 , 2012 . this decrease was the net result of decreases in all components of operating working capital . trade receivables from customers , net , as a percentage of fourth quarter sales , annualized , for 2012 was 17.6% ( 17.6 % ) , down slightly from 17.9% ( 17.9 % ) for 2011 . days sales outstanding was 61 days in 2012 , a one day improvement from 2011 . inventories on a fifo basis as a percentage of fourth quarter sales , annualized , for 2012 was 13.2% ( 13.2 % ) up slightly from 13.1% ( 13.1 % ) in 2011 . inventory turnover was 4.8 times in 2012 and 5.0 times in 2011 . total capital spending , including acquisitions , was $ 533 million , $ 446 million and $ 341 million in 2012 , 2011 , and 2010 , respectively . spending related to modernization and productivity improvements , expansion of existing businesses and environmental control projects was $ 411 million , $ 390 million and $ 307 million in 2012 , 2011 , and 2010 , respectively , and is expected to be in the range of $ 350-$ 450 million during 2013 . capital spending , excluding acquisitions , as a percentage of sales was 2.7% ( 2.7 % ) , 2.6% ( 2.6 % ) and 2.3% ( 2.3 % ) in 2012 , 2011 and 2010 , respectively . capital spending related to business acquisitions amounted to $ 122 million , $ 56 million , and $ 34 million in 2012 , 2011 and 2010 , respectively . a primary focus for the corporation in 2013 will continue to be prudent cash deployment focused on profitable earnings growth including pursuing opportunities for additional strategic acquisitions . in january 2013 , ppg received $ 900 million in cash proceeds in connection with the closing of the separation of its commodity chemicals business and subsequent merger of the subsidiary holding the ppg commodity chemicals business with a subsidiary of georgia gulf . refer to note 25 , 201cseparation and merger transaction 201d for financial information regarding the separation of the commodity chemicals business . in december 2012 , the company reached a definitive agreement to acquire the north american architectural coatings business of akzo nobel , n.v. , amsterdam , in a deal valued at $ 1.05 billion . the transaction has been approved by the boards of directors of both companies and is expected to close in the first half of 2013 , subject to regulatory approvals . in december 2012 , the company acquired spraylat corp. , a privately-owned industrial coatings company based in pelham , n.y . in january 2012 , the company completed the previously announced acquisitions of colpisa , a colombian producer of automotive oem and refinish coatings , and dyrup , a european architectural coatings company . the total cost of 2012 acquisitions , including assumed debt , was $ 288 million . dividends paid to shareholders totaled $ 358 million , $ 355 million and $ 360 million in 2012 , 2011 and 2010 , respectively . ppg has paid uninterrupted annual dividends since 1899 , and 2012 marked the 41st consecutive year of increased annual dividend payments to shareholders . we did not have a mandatory contribution to our u.s . defined benefit pension plans in 2012 and we did not make a voluntary contribution to these plans . in 2011 and 2010 , we made voluntary contributions to our u.s . defined benefit pension plans of $ 50 million and $ 250 million , respectively . we do not expect to make a contribution to our u.s . defined benefit pension plans in 2013 . contributions were made to our non-u.s . defined benefit pension plans of $ 81 million , $ 71 million and $ 87 million for 2012 , 2011 and 2010 , respectively , some of which were required by local funding requirements . we expect to make mandatory contributions to our non-u.s . plans in 2013 in the range of approximately $ 75 million to $ 100 million . the company 2019s share repurchase activity in 2012 , 2011 and 2010 was 1 million shares at a cost of $ 92 million , 10.2 million shares at a cost of $ 858 million and 8.1 million shares at a cost of $ 586 million , respectively . no ppg stock was purchased in the last nine months of 2012 during the completion of the separation of its commodity chemicals business and subsequent merger of the subsidiary holding the ppg commodity chemicals business with a subsidiary of georgia gulf . the company reinitiated our share repurchase activity in the first quarter of 2013 . we anticipate spending between $ 500 million and $ 750 million for share repurchases during 2013 . we can repurchase nearly 8 million shares under the current authorization from the board of directors . in september 2012 , ppg entered into a five-year credit agreement ( the "credit agreement" ) with several banks and financial institutions as further discussed in note 8 , "debt and bank credit agreements and leases" . the credit agreement provides for a $ 1.2 billion unsecured revolving credit facility . in connection with entering into this credit agreement , the table of contents .