Percentage change (increase or decrease).
* very important *
Can be used to calculate change in GDP (by measuring the change in the GDP deflator), or an annual change in the CPI to measure the inflation rate among other things.
[(New number - Original number) / Original number] x 100
- 2011 GDP deflator = 108.2
- 2012 GDP deflator = 109.6
[(109.6 - 108.2) / 108.2] x 100
% change in GDP from 2011 to 2012 = 1.29%