What is the average age at which Australians start to use cannabis?

Among Australians aged 14 years and older who have ever used cannabis, the average age at which they first tried it was 19 years.

Among Australians aged 14-24 years who have ever used cannabis, the average age at which they first tried it was 17 years.

Source: Australian Institute of Health and Welfare (AIHW). 2013 National Drug Strategy Household Survey.