In 2016, for the first time ever, natural gas could overtake coal as the main source of electricity in the U.S.

A decade ago, coal accounted for almost 50 percent of electricity generated in the U.S. but in 2015, it was down to 33 percent. The dramatic decline has been fueled largely by utilities switching from coal to natural gas, as gas prices have fallen in recent years because of the fracking boom.

Now, the Energy Information Administration is predicting that in 2016, natural gas will surpass coal as the country’s leading power source, although only by a narrow margin.

It this could be the beginning of a trend though, as environmental regulations coupled with increasing amounts of both natural gas and renewables push coal to the margins.