Already in 2010 a survey of the International Council on Security and Development showed that 92 percent of Afghanis didn't know anything about the 9/11 attacks and therefore had no clue why the Americans are there.
Last year, RT.com made a little special on that:
My personal vote for most painful quote: "One building was destroyed there? How many did they destroy here? They say they're going to help. Where's the help?"