A new survey from Expedia finds that American workers typically leave four full days of vacation on the table each year – averaging just 11 of the 15 days available to them. Multiply that by the 122 million full-time workers in the country and it works out to 500 million days left unused. Put another way: Every year, we collectively ignore more than 1.3 million years of available vacation.

The good news is, that’s a lot better than South Korea, where workers only take an average of 6 of their available 15 days per year. But when compared to the global figures, we let more of that paid free time go to waste. Worldwide, workers fail to use 20% of their available vacation.

“A healthy work-life balance is critical, not only to give workers a chance to enjoy their lives outside of the office, but also to recharge, making you more productive when you get back to work,” said John Morrey, Vice President and General Manager of Expedia.com.

Expedia, of course, has a vested interest in getting people to use their time off. But its data seems in line with other studies, showing that Americans simply don’t use their allotted vacation.

“For some workers, vacation is a right, and for others, it’s a guilty pleasure,” said Morrey. “Some workers also fear that their bosses will disapprove.”

Americans get less paid time off, still don’t use it all

The Expedia survey looked at the vacation habits of over 9,200 employed adults over 26 countries.

Europeans get twice the amount of paid time off that Americans do. And they tend to use that vacation time the most. Workers in Germany, France, Italy, Spain, Sweden, Denmark and Finland all get 30 days off per year, according to the study. The French, Germans, Spanish and Finnish use virtually all of those days. (While not a European country, Brazilians also use all of their 30 vacation days.)

The Danish use 28 of the 30. And Italians and Swedes fail to use the most days, taking 25.

Joining South Korea toward the bottom of the work-life balance list is Japan, whose workers take just 12 of their offered 20 days. And Malaysians, where employees only use 10 of their available 14 days.

Never disconnected

Even when workers do take advantage of their vacation days, many find they’re unable to completely leave work behind. A full 25% of the workers Expedia spoke with worldwide said they check their work email and phone messages once per day while on vacation. (That number jumps to 42% for workers in Hong Kong.) And 34% say they ignore the demands of the office.

Whether its the disparity of the days off Americans get compared to European co-workers or the fact that Americans tend to not take the days they have, the majority of US workers (some 53%) tell Expedia that they feel “somewhat or very” vacation deprived. That’s in line with the global average.

That doesn’t compare with workers in the UAE, though. Despite having (and taking) 30 days a year, 76% of the employees Expedia spoke with in the survey said they still felt “somewhat or very deprived” when it comes to vacations.

While there’s certainly nothing wrong with being a dedicated employee, stepping away from the desk is vital to enjoying and being productive at your job. Some companies (like Netflix, which offers its employees unlimited vacation and parental leave) even go out of their way to encourage employees to take advantage of their paid time off to help them gain perspective, something that can ultimately make them more valuable to the company. (One San Francisco startup even covers the tab for vacationing workers.)

Curious about how all of the countries in the survey stacked up? Here’s a look at the full list.