An interesting video from Dan Mitchell, from the Cato Institute, explaining the Rahn Curve and the curse of big government:

Australian Government spending:

The Australian Government spending as a proportion of GDP as of 2007-2008 was 24 percent (source). In the above video, Dan references a number of studies that show that the optimum government spending to GDP ratio should be between 15 to 25 percent. Although keep in mind this is only the federal level of spending. If we were to include local, state and federal spending, then total government spending would be 34.2 percent of GDP (source). This would put us on downward slope of the Rahn curve.