WASHINGTON, D.C. (CNA).- Fifty-one percent of the reported fire incidents at U.S. houses of worship between 1996 and 2015 were determined to be caused by arson, according to a recent analysis by the Pew Research Center.

Church fires are investigated and classified by the Bureau of Alcohol, Tobacco, Firearms and Explosives as accidental, bombing, arson, threat or undetermined.

Statistics show that just over half of the approximately 4,700 fires reported at houses of worship between 1996 and 2015 were ruled intentional.

There has been little change in the percentage of church fires caused by arson over the years, Pew says. However, there have been decreases in overall numbers of church fires, as well as numbers of intentional church fires.

"Between 1996 and 2000, an average of 191 intentional fires were reported each year, accounting for 52 percent of all church fires," the Pew analysis reads. "That average dropped to 74 intentional fires per year between 2010 and 2014, or 48 percent of all church fires."

In the first half of this year, 29 out of 79 reported fires at houses of worship have been ruled acts of arson. On August 2, there were two reports of bomb explosions at churches in Las Cruces, N.M.

In 1996, a congressional report found that black churches in the South were disproportionately targeted for church arson. That same year, President Bill Clinton signed the Church Arson Prevention Act and established the National Church Arson Task Force to fight these incidents.