An anti-narcotics worker carries a bag containing cocaine during a drug incineration in Lima September 12, 2013. REUTERS/Mariana Bazo A new study used governmental data to prove that the war on drugs war has been largely ineffective.

The research is the “first global snapshot” of law enforcement's progress in reducing drug supply, according to lead author and University of British Columbia professor Dr. Evan Wood.

Trends in drug supply were observed using drug prices and purity over time because drugs are generally cheaper and more pure when sellers are less motivated to dilute their product to increase yields.

Based on seven major illegal drug data surveillance systems, the researchers found that heroin, cocaine, and marijuana became significantly cheaper and more potent from 1990 to 2007 (the last year for which data is publicly available).

This indicates, according to the authors, that drug supply has increased despite drug seizure trends having remained stable or increased.

“By every metric, the war on drugs — which is estimated to have cost North Americans over the last 40 years over a trillion dollars — has really been hugely ineffective,” Wood, who founded of the International Centre for Science in Drug Policy, told The Star. “Drugs are more freely and easily available in our society than they’ve ever been.”

The average purity of heroin and cocaine in the U.S. increased by 60% and 11%, respectively, while weed became 161% more potent.

At the same time, the average heroin and cocaine prices dropped by 81 and 80 %, respectively, while the price of cannabis fell by 86% over that time. (All prices have been adjusted for inflation and purity.)

Here's marijuana:

The study notes that it could not look into methamphetamines because of lack of available data across regions, but the trend is reportedly the same: From 2007 to 2011, the purity of available meth in the U.S. skyrocketed while the price tumbled from $290 per pure gram to less than $90.

The authors conclude that the study is meant to highlight "the need to re-examine the effectiveness of national and international drug strategies that place a disproportionate emphasis on supply reduction at the expense of evidence-based prevention and treatment of problematic illegal drug use."