Glad you asked - according to the FBI, two-thirds of murder cases get solved. What percentage of drug 'crimes' do you reckon even get detected ... 2 in 3000 maybe?
But we are still having murders. Is that a failure or a success? By the standards the dopers want to use, the war on murder is a total and complete failure, and we should just stop fighting against murder because people are going to do it anyway.