Since 9/11, almost as many Americans have died at the hands of far-right-wing extremists as have been killed by radical Islamists - 106 and 119, respectively - a new report by the nonpartisan Government Accounting Office shows.

The GAO also said that despite more than $50 million being spent by the Dept. of Homeland Security (DHS) in 2016 to counter the growth of violent extremism in the U.S., there is no mechanism in place to measure whether efforts apart from surveillance and law enforcement have been effective.

Of the 85 violent extremist attacks since Sept. 12, 2001, which resulted in 225 deaths, 62 - or 73 percent - were by far-right groups or individuals, the GAO report says.

While more of the 225 deaths were attributed to radical Islamists, the GAO said that 41 percent of those killings happened in a single incident, the 2016 attack on a club in Orlando. The shootings at the Pulse nightclub left 49 dead and 53 wounded.