WEST LAFAYETTE, Ind. (AP) – A new Purdue University study says grain bin entrapments and other confined space accidents on the nation’s farms fell to their lowest level in a decade last year. Iowa led the nation with seven incidents.

Purdue’s study shows the U.S. had 47 entrapments in grain bins and other confined spaces in 2015. That’s 34 percent less than 2014’s 71 entrapments and the fewest since 46 were recorded in 2006. Purdue says 25 people died last year in entrapments, down from 31 in 2014.

But Bill Field, a Purdue professor of agricultural safety and health, says many nonfatal entrapments go unreported each year because there’s no mandatory national reporting system.

In addition to Iowa, other states reporting grain bin entrapment deaths include: Arkansas, Connecticut, Illinois, Indiana, Kentucky, Minnesota, Nebraska, North Carolina, North Dakota, Ohio, Wisconsin and South Dakota.