American workers have left unused more than half of their allotted vacation days over the past 12 months.

NO VACATION MEANS empty hotel rooms. On average, U.S. workers have taken only half (54 percent) of their allotted vacation days in the past 12 months, reported Glassdoor, a jobs and recruitment website.

Project Time Off’s separate analysis says if the 54 percent of that untapped vacation was used it would generate $128 billion in direct spending.

And when they do go on a holiday, two out of three employees, or 66 percent, work, said Glassdoor. That percentage is up 5 percent from three years ago.

Harris Poll conducted survey in March and April, hearing from 2,224 adults. Glassdoor released the findings in late May.