A new study found that Americans are working harder and taking less vacation time.

Half of Americans who work 50 hours a week or more don’t use all of their available vacation days. One in three Americans who do take vacation end up working during it.

Americans took an average of 20 days of vacation in 2000. In 2015, the average was 16 days.

The poll was conducted by the Robert Wood Johnson Foundation, the Harvard T.H. Chan School of Public Health, and NPR.