The Annenberg Political Fact Check has taken on the “Mexican crime guns come from the U.S.” factoid and agree with Fox News that the 90% statistic cited by anti-gun politicians is bogus. They back up Fox News’s central contention that the 90% reflects only the guns that are successfully traced, a sample which is very heavily biased towards guns from the U.S. They estimate the true number at 36%, a bit higher than the 17% calculated by Fox News. (Annenberg says one of the figures Fox was calculating from is wrong.) Either way, it’s a long long way from 90%.