According to the paper, Americans work nearly 25% more hours than Europeans. In other words, that’s an additional 258 hours per year or an hour more each weekday. The working paper, which has not yet been published, was written by three economists—Alexander Bick of Arizona State University, Bettina Bruggeman of McMaster University in Ontario, and Nicola Fuchs-Schundeln of Goethe University Frankfurt.

The authors looked at 18 European countries and the U.S. Of the 19 total countries they examined, the U.S. came out on top averaging 26.1 hours per person per week; Italy worked the fewest hours with an average of 18.4 hours.

The study looked at hours per person. It doesn’t only include people currently in the workforce, but those either retired or taking time off for some other reason, like unemployment or vacation. Ultimately, it doesn’t measure productivity, but rather total time spent at work.

The disparity in hours worked between the U.S. and Europe could be explained in various ways or, more likely, is an amalgamation of numerous different reasons. Taxes, for one, are much higher in Europe than in the U.S. According to Bloomberg, that gives European workers less incentive to work longer hours. It may also have something to do with labor unions, which generally have more power in Europe than they do in the U.S.

Additionally, Europeans tend to get generous pensions, rather than investment plans like the 401(k) many American workers receive. As a result, there are more American workers over 65-years-old now than there have been at any point in the past 50 years.