In 2016 it was 5.5% of GDP. Highest was 10.63 % in 2011.

This reflects two major problems in Australia:

1. Wages in Australia are high which makes resource projects expensive.

2. All resource projects over the past 2 decades have blown their budget making Australia less attractive as a destination for investment because the risk of unsatisfactory returns on the investment is high.

https://www.theglobaleconomy.com/Australia/Natural_resources_income/