. the repurchase program does not include specific price targets or timetables . as of december 31 , 2007 , the company had acquired 58 million common shares at a cost of $ 2.520 billion under the program , including 16 million common shares acquired during 2007 at a cost of $ 822 million and 42 million common shares acquired during 2006 at a cost of $ 1.698 billion. .