Okun's Law, a rule used by economists to connect GDP growth and unemployment rate forecasts, has not been consistently accurate in predicting unemployment rate declines during recent economic expansions. Changes in the labor market since the 1960s have affected its reliability. The percentage decreases in the unemployment rate in the third to fifth years of the last three expansions have been very similar, indicating the importance of people moving in and out of unemployment in explaining changes in the unemployment rate.