Americans are really bad at ditching their cubicles for a cabana. According to a new survey conducted by online travel firm Expedia, U.S. residents received an average of 15 annual vacation days in the past year, but they only took 12. Collectively, the nation threw away 375 million vacation days.

Expedia’s 2016 Vacation Deprivation Report examined vacation habits among 9424 employed adults in approximately 28 countries around the world. Not surprisingly, the number of paid days off—and how people use them—varied dramatically among workers in North America, South America, Europe, and Asia, with the U.S. lagging behind many nations.

People in Europe, Brazil, and the United Arab Emirates received the most vacation days—and for the most part, they used them. Workers in Finland, France, Spain, the UAE, and Brazil were all provided with 30 days of leave, and took full advantage of their time off. German and Italian residents also received 30 days vacation, and used 28 and 25 of them, respectively. Meanwhile, 25 vacation days were the norm in Switzerland, Sweden, Norway, Denmark, the United Kingdom, and Austria (as was using them).

Workers in North America and Southeast Asia weren’t so lucky. Employees in the U.S., Canada, Mexico, South Korea, and Thailand only received 15 days of vacation.

Wondering which countries took the fewest vacation days? That would be South Korea, where people took only eight of their 15 (the least among all 28 countries) and Japan, where people were given 20 days but used half that amount.

Why aren't Americans escaping the office for some much-needed R&R? Twenty-two percent of U.S. survey respondents said they felt like they should wait a year or more after accepting a new job before taking a day off; 14 percent felt guilty (6 percent felt so guilty, they skipped out on vacation altogether); and 9 percent said they were worried that their bosses would view them negatively if they utilized all their vacation days. It's no surprise, then, that 29 percent of Americans said they typically went one year or longer between vacations, and 25 percent of Americans reported feeling “very vacation deprived.”

Many people view vacations as a luxury, but they’re actually a health necessity. Taking time away from work to de-stress can lower your risk for heart attack, make you feel happier and calmer, and help you live longer. Not only that, time off actually makes you better at your job: One survey conducted by accounting firm Ernst & Young found that workers who take more vacation time receive better performance reviews and are less likely to leave the firm. Instead fearing that a vacation will make you seem lazy, uncommitted, or replaceable, view it as a way to recharge and become a more energetic and productive employee.