Petrol is cheap again....except in Australia

On the weekend I was talking with my brother. I was saying to him, "Isnt it awesome that petrol is so low again"

"What do you mean?", he says to me "Its still $1.50 per litre."

Then today I see this article on NineMSN. Im shocked. When I first got to the USA 3 months ago, fuel was $4.20/gallon (or around $1.10/lt). At the same time in Australia it was $1.56/lt.

Now this morning I filled up and it was $2.70/gallon. Thats around 70c/lt...and thats for premium unleaded!

Lets work out that percentage. In the US it drops by nearly half. Ill let you work out the Australian percentage. How come it hasnt dropped by the same amount in Australia?...and dont tell me its the exchange rate...