This is Why We Should Worry

"a distinct shift in the dominant ideologies of these terrorist groups over time, with the proportion of emerging ethnonationalist/separatist terrorist groups declining and the proportion of religious terrorist groups increasing"

http://www.washingtonsblog.com/2013/05/muslims-only-carried-out-2-5-percent-of-terrorist-attacks-on-u-s-soil-between-1970-and-2012.html