What’s worse, 15 percent took none of their vacation days at all. The rest took some portion of the days they were allotted, according to the data released Thursday by employment website Glassdoor.

Even when employees took vacation, many ended up working. More than half of the employees who took vacation said they did some work while they were supposed to be off, according to the Glassdoor data.

Glassdoor’s data is based on a Harris Poll of about 2,000 adults, including about 1,000 full- and part-time employees who were included in the questions about vacation.

The findings are in keeping with other research showing that Americans are likely to leave at least some of their vacation on the table, even when they are granted it.