Tue Jun 18, 9:27 AM ET PERTH, Australia (Reuters) - Better, more efficient growing techniques are slashing marijuana prices in Australia and pushing up consumption. Prices of the weed have fallen in real terms by almost 40 per cent over the past 10 years, according to a survey by the Economic Research Centre at the University of Western Australia. Marijuana remains illegal here, but smoking or possessing small amounts has been decriminalized in most Australian states. "Even though marijuana is an illegal substance in Australia it seems that the application of modern production techniques, particularly hydroponic techniques, has led to a substantial increase in supply," said Professor Ken Clements who led the research. "This, in turn, has led to the sharp fall in price we have recorded," he told Reuters on Tuesday. According to the research, an ounce of marijuana leaf in Sydney in 1990 would have cost A$438 (US$244). In 1999, the date of the research, the price had fallen to A$275. Perth had the cheapest marijuana in 1999 with an ounce costing A$250, but was one of the few places to record an increase. An ounce costs A$210 in 1990. The falling price of marijuana sparked a 15 per cent rise in consumption, the survey found. "Australians are widely recognized as big beer drinkers but what we've found is that they are also among the biggest marijuana consumers in the world," Clements said.