Question 600982
I'm not exactly sure how CPIs work, but my guess is that you're comparing this 80% increase with the percentage increase of the CPIs over this time period.



This percentage increase is...


Percent Increase = [(New - Old)/Old] * 100


Percent Increase = [(215.3-130.7)/130.7] * 100


Percent Increase = [84.6/130.7] * 100


Percent Increase = 0.647283856159143 * 100


Percent Increase = 64.7283856159143%



So in 1990, the CPI was 130.7 and over this entire time period, it increased to 215.3 in 2008. This percentage increase was roughly 64.73%



Compare this with the percentage increase of the price of the plane ticket and you can see that the price of the plane ticket clearly grew more.