I believe the GDP numbers...it's probably all heroin.
http://www.lewrockwell.com/orig6/velvel5.html
11. Heroin is made from opium. The Taliban had largely eliminated opium
production in Afghanistan (although the U.S. Drug Enforcement
Administration later claimed the Taliban did this only to raise the
price of the large stockpiles of opium the Taliban had in warehouses).
In 2001, the year when we began military operations against Afghanistan
late in the year, opium production in Afghanistan was down to 74 metric
tons. (P. 155.) Largely because the warlords who did most of our
fighting for us wanted opium grown so that they could make gazillions
from it, opium production soared after we threw out the Taliban. It rose
to 1278 metric tons in 2002, then more than doubled in 2003 and nearly
doubled again in 2004. (P. 155.) By 2004, "Afghanistan was producing 87
percent of the world's opium supply," which "generate[d] $7 billion
worth of heroin." (P. 156.) (Nice record George/Dick/Don.). We turned a
blind eye, since our buddies, the warlords, were doing it.
Afghanistan became, and apparently is today, what Risen calls a
"narco-state." (Pp. 151,155-166.)