"Fires burned 10% of Australia's land surface on average every year in 20th century
In this century, it burned 6% (2001-19)
We now have the data for 2019-20, the year with "Australia ablaze":
4% (3.95%)" (@BjornLomborg)
https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2005.00920.x
http://globalfiredata.org/analysis.html
https://www.nature.com/articles/d41586-020-02306-4
