When Anders took out his first two-year membership with Maxi…

When Anders took out his first two-year membership with Maxima Gym in 2004, the fee was $540.00.  He renewed his membership three times; in 2006 for $580.00, in 2008, for $600.00, and again in 2010, for $630.00. What is the overall rate of inflation (percentage change in prices) for Anders’ gym membership?