The estimated number of terrorists in the world (all numbers were pulled from the 2012 State Department report on terror and all numbers were rounded up very generously, feel free to do the same for the 2013 terror report: http://www.state.gov/j/ct/rls/crt/2013/224829.htm) is 184,000 the data came out before ISIS so we'll add 30,000. 214,000/1,600,000,000=0.00013375 0.00013375x100=0.013375% So why then do we call for all Muslims to apologize whenever one of them does something wrong, do you do the same when a Christian does something because of his faith? Also why do people ignore it when they do condemn the actions of terrorists, the same people who shout for a public condemning never seem to be listening when they get it. Edit 1: Including the other terrorist organizations still gives a percent less than 1, I will provide you with evidence to back it up later today. Edit 2: Yes, the data is a bit old but terrorist groups do not multiply (they grow slowly) so the numbers should still be reasonably accurate. Souce: https://www.techdirt.com/articles/20140506/14033627137/how-many-terrorists-are-there-not-as-many-as-you-might-think.shtml