The findings by Integrity Watch Afghanistan showed corruption is rampant in all areas of life in the country. IWA said the survey, its second, is designed to increase transparency, integrity and accountability.
"The Afghan population as a whole paid twice as much in 2009 as it had paid in 2006. Bribery today represents a burden of $1 billion on the Afghan GDP," the group said in a news release on its Web site.
"One adult in seven experienced direct bribery in Afghanistan in 2009, while 28 percent of Afghan households paid a bribe to obtain at least one public service."
The group surveyed 6,500 respondents in 32 provinces at the end of last year, focusing on petty or administrative corruption, which affects the people the most, the report said.
IWA said corruption, among other things, threatens the legitimacy of state-building, feeds frustration and support for the insurgency, and impedes the rule of law.