. the plan has two purchase periods , the first one from october 1 through march 31 and the second one from april 1 through september 30 . for the years ended december 31 , 2012 , 2011 and 2010 , employees purchased 1.4 million , 2.2 million and 2.7 million shares , respectively , at purchase prices of $ 34.52 and $ 42.96 , $ 30.56 and $ 35.61 , and $ 41.79 and $ 42.00 , respectively