I doubt that is accurate too, if you were to really look at some of the cases. Easy to spot, some of them, for example, this fine fellow from Afghanistan was most likely a "refugee"...
Zazi was born in a village in Paktia Province, Afghanistan. He has two sisters and two brothers. At the age of 7 in 1992, he and his family moved to the city of Peshawar in Pakistan where they settled as Afghan refugees.
In 1999, he and the family left Pakistan and immigrated to New York City. They moved into a two-bedroom apartment in the Flushing, Queens section of the city. Mohammed Wali Zazi, Najibullah's father and now a naturalized U.S. citizen, found work as a New York City taxi driver.
Zazi underwent weapons and explosives training at an al-Qaeda training camp in Pakistan in 2008. On September 9, 2009, he drove from his home in Aurora, Colorado, to New York City, intending to detonate explosives on the New York City subway during rush hour as one of three coordinated suicide "martyrdom" bombings. Spooked, however, by surveillance by U.S. intelligence, and warned by a local imam that the authorities were inquiring about him, he abruptly flew back to Colorado. He was arrested days later.
Here's a little exercise for you. Look up how many people were murdered in the US last year. Then look up how many were killed by immigrants from the countries in question.