One in five Massachusetts residents bets on sports, a figure that’s grown from about 13% in 2014 and roughly tracks business in states where sportsbooks are already legal.

“We know that Massachusetts is quite a sports crazy state already,” said Rachel A. Volberg, a University of Massachusetts Amherst professor and the principal investigator on two major studies funded by the Massachusetts Gaming Commission.

What’s more, sports betting is available in every neighboring state except Vermont.

“People in Massachusetts have been bombarded by that advertising even though sports betting is not legal here,” she said. Her research also shows that sports bettors can have higher rates of problem gambling, but only because they tend to be involved in more types of gambling than other types of betters who might focus on one activity.