Colombia ? Cocaine prices in the United States have dropped and the drug’s purity increased, despite years of effort and nearly $5 billion spent by the U.S. government to combat Colombia’s drug industry, the White House drug czar acknowledged in a letter to a key senator.

The drug czar, John Walters, wrote Sen. Charles Grassley, R-Iowa, that retail cocaine prices fell by 11 percent from February 2005 to October 2006, to about $135 per gram of pure cocaine – hovering near the same levels since the early 1990s. In 1981, when the U.S. government began collecting data, a gram of pure cocaine fetched $600.

Colombia supplies 90 percent of the cocaine consumed in the United States.

Colombia’s president, Alvaro Uribe, is set to meet with President Bush on Wednesday at the White House to discuss U.S. support for Plan Colombia, the anti-narcotics and counterinsurgency program that has cost American taxpayers more than $4 billion since 2000.