The formula for percent change (PC) is:
((end rate - initial rate) / initial rate) * 100
On the Statistic tab in a Rate session, if you are calculating trends, you must set PC End Points to "One Year" or "Two-Year Average". If PC End Points is set to "One Year", then the initial rate is the first year of the range and the end rate is the last year. If PC End Points is set to "Two-Year Average", the software uses an unweighted average of the rates for the initial two years and last two years in the range for PC End Points.