Don't worry, you read all those zeros correctly - $2.5 billion.  That's the estimated amount of bribes paid by Afghans in 2009, according to a recent report from the United Nations Office on Drugs and Crime.

As I wrote earlier, corruption is a major problem in Afghanistan.  It saps what little legitimacy the Karzai government retains and prevents the regime from providing even the most basic services to the populace.  To put that figure in perspective, it constitutes roughly 23% of GNP.  Spending 23% of GNP on a single sector is problematic for any economy, but spending it on bribes in an already faltering and fragile state is disasterous.

Rory Stewart highlighted this problem in a recent article, writing,

The effective, legitimate Afghan government, on which the entire counterinsurgency strategy depends, shows little sign of emerging, in part because the international community lacks the skills, the knowledge, the legitimacy, or the patience to build a new nation.

His whole article is well worth reading, but the takeaway remains the same - no amount of American intervention can succeed without a real government in Afghanistan.