And in a poll in 2005, the OECD found that Mexicans were actually the most likely to be satisfied with their jobs, even though they get a relatively modest 23 days off of combined vacation and holiday time.

So why are the world's workaholics seemingly so content? And why is a country with such middling vacation requirements, the Netherlands, also the happiest country?

The EU's vacation policies also meant it was not easy to find the answer.

"I do not read e-mail until Monday August 26," one auto-response told me last week.

I was assured by one that they would "read your message when I get back [in late August] and get back to you in due course."

Fortunately, a few were willing to interrupt their breaks in order to fill me in.

Job security: Southern Europeans are currently making less and fearing layoffs amid their ongoing recession, factors that are likely driving down their satisfaction levels.

Meanwhile, Dutch incomes are higher than average for the European Union, and "the crisis which has engulfed the rest of Europe hit The Netherlands fairly late, so the fear of job loss there is less and fairly new," said Shawn Donnelly, an economics professor at the University of Twente in the Netherlands.

Hours: The Dutch have incredibly short work schedules, and only about a quarter of women there are employed full-time, despite the government urging that they work more. Who wouldn't love a job that lets you do art projects or get coffee with friends at 2 p.m.?

And even for full-time workers, work-life balance reigns:

"The Dutch have a 9 to 5 mentality much more than other countries have. If it's 5:30, and you aren't at home with your family or on your way there, you're a freak. That means they can detach themselves from the stress more easily than elsewhere," Donnelly said.

As a counter-example, see the Japanese: They get 10 guaranteed days off, but their long hours and high-stress jobs might be what's bringing down job satisfaction. Some surveys also show that the Japanese and Italians are more likely to leave their state-mandated vacation days unused.

The "minimum vacation" factor: This is probably the strongest argument for establishing a country-wide norm for time off. Vacation laws tend to work like minimum wages, Lowell Turner, a professor of international labor at Cornell University, explained. Saying you have to pay workers at least $7.25 an hour doesn't mean everyone in the country makes $7.25 -- it just means you can't pay them less. But from that point, companies compete for workers by piling on more money.

The same theory holds for vacation time in countries that have statutory minimums (and their strong labor unions further help drive up the number of days off). Donnelly said he gets almost nine weeks -- much more than the Dutch minimum.

And it's worth remembering that in countries without a time-off mandate, workers often do get time off at their employer's discretion. According to the CEPR study, about 90 percent of full-time and high-wage American workers get vacation time and paid holidays. But that figure is only about 50 percent for the lowest-earning workers. It's likely that if Randstad had polled only the bottom 25 percent of wage-earners, the satisfaction numbers would look completely different.