Look here and in the links provided - just be careful with Prescott (Blanchard's paper from my previous post criticizes exactly this argument of Prescott). Some excepts:

Per capita hours fell during 1970-2002 for most OECD countries and by over 20% in France; but they rose in several countries, and by fully 20% in the United States...

Two factors underlie the divergence between the United States and Europe since 1970 in hours worked per capita. First, hours worked per capita are influenced by the share of the population actually working, and the employment rate has increased more strongly in the United States than in most other OECD countries....

    Secondly, the length of the average work year has not declined as much since 1970 in the United States as it has in most European countries, including France and Germany. In fact, annual hours per employed person have remained more or less unchanged for US workers since 1980. By contrast, reductions in the length of the standard work week have continued in most other high-income countries, as have increases in annual days off for public holidays and vacation.

In short, Americans work more, both as a nation and as individuals. Not a big surprise they produce more.