American workers put the hours in
The average Norwegian worker is almost 20% more productive than his US counterpart, the International Labour Organisation (ILO) has calculated, exploding the image of American efficiency.
French and Belgian workers, too, produce more economic value for every hour worked than do Americans.
But the same figures showed that US had the edge overall, since workers there put in more time than Europeans.
As a result of short holidays and long hours, the average US worker produced $60,728, compared with just $54,333 in the EU.
Americans now work the same hours on average - 1,825 during last year - as the Japanese, who used to have an unrivalled reputation for industriousness.
The figures underline the differing work cultures on both sides of the Atlantic.
The US has always tended to have more of a hard-work culture than Europe, but this has become especially marked in recent years.
Europeans don't always show up
In Europe, meanwhile, there has been considerable political pressure to keep working hours short, trade unions remain strong and work is more often disrupted by strikes than in the US.
But the ILO figures indicate that this does little harm to overall productivity.
"If you work 15 hours a day, of course there are hours when you are not as productive as if you only work six hours a day," said Dorothea Schmidt, an ILO economist.
Generalisations can be dangerous, Mr Schmidt warned.
Shorter working days alone do no guarantee higher per-hour productivity, as shown by the many other European countries that lag the US.
And US productivity is growing quickly, unlike Europe as a whole, mainly thanks to greater investment in labour-saving technology.
In certain fields, technology can have dramatic effects: an agricultural worker in the US, for example, produces 650 times more than a worker in Vietnam.
The European Commission is concerned that EU firms have made too little effort to modernise their production technology, and that Europe will eventually start to fall behind the US as a result.