You must be a very special individual to believe that you understand inflation. The calculation in real terms is complicated and involves demand-pull, cost-pull measures etc and is derived from some 80+ attributes. The standard presentation is through CPI which is measured by the ABS every quarter and also presents an overall level annually. Current CPI for Australia is 6.9%. Now, I agree that CPI has its limitations, however it is probably the most easiest measure to understand, even if it is a crude measure.
As for changes in the calculation. You're right, and wrong at the same time. The measure variables have changed and expanded to encompass greater variables. The calculation, however has not changed since its introduction in 1960.