每工作小时产量的增长率是人均收入增长的主要因素。 从九十年代中期开始，这一增长率在欧洲大多数国家都有所减缓，而美国则上升，从而逆转了长达十年的模式。
Beginning in the mid-1990’s, the rate of growth in output per hour worked – a key factor behind the rise in per capita income – slowed in most European countries while it rose in the US, reversing a decades-long pattern.