Found this some months ago while researching the history of the Petroleum Operator trade within the Australian Army. It is very poignant as it reflects the same concern as today. If I read it correctly back in 1976 Oil refinerys held about 17 weeks/ 199days of processed fuels way above what we have now. It is a good reference to gage the the effect of federal political decisions over the proceeding 40 plus years.
Oil supply and National Security by Lt Col Ball
https://www.army.gov.au/sites/g/file...8_sep_1976.pdf