Australian Drug Statistics

In 2004, 38% of Australian's aged 14 year's and over had used an illicit drug in their life time
Marijuana / cannabis is the most common illicit drug used, with one in three persons (34%) having used it at least once in their lifetime
In 2004, 9% of Australian's aged 14 and over had used methamphetamine (crystal) in their lifetime
In 2005, 46% of injecting drug users had overdosed at some point in their lives
In 2004/5, marijuana / cannabis accounted for 71% of illicit drug arrests
In 2005, one in ten prisoners were imprisoned for drug related offences
In 2003/04, 88% of juvenile detainees had used an illicit substance 6 months prior to their arrest and 70% were intoxicated at the time of their offence
From 1991 to 2004 the use of cocaine has increased by 42% and the use of ecstasy (includes designer drugs) increased by 309%
18% secondary students aged 12 -17 have used marijuana /cannabis at least once

The following gives you some comparisons of Australia drug usage verses other English speaking countries and is based on the percentage of population.

Australian and New Zealand have the second highest usage of marijuana, Canada the highest and USA the third highest
Australians have by far the highest usage of ecstasy and New Zealand the second highest. Australia's usage is double that of the UK and four times that of the USA
Australian's consumption of cocaine is twice that of New Zealand
Australian's usage of amphetamine (speed) is the highest, New Zealand is second, with USA and UK being equal third
UK has the highest use of opiates, Ireland and the USA are equal second and Australia and New Zealand equal third

Reference:
Australia Institute of Health and Welfare 2007.
Statistics on drug use in Australia 2006.
Drug Statistics Series No. 18. Cat. No. PHE 80. Canberra: AIHW.