That is a significant drop for sure and it must be hurting the drug cartels based in Colombia. Yet, my guesstimation would be that what is lost on the merry-go-round is made up on the swing. Someone else is more than likely picking up Colombia's slack.
What the reduction does say though is that the police in Colombia are having success in their crop eradication efforts, the removal of drug laboratories, and the prosecution of drug bosses. This has seen more than a million hectares of drug crops destroyed. In another success story more than 74 tonnes of cocaine has been seized in the first three months of 2008.
I still wonder about legalization and take the black market out of the trade. Another debate for another post, I suppose!