It is sketchy, but mainly it's the headline that's misleading. For the 64% number they used all crimes, including immigration. For non-immigration crimes the percent of total is stated as 15%, but they also make sure to note that they are only 7% of the population, meaning their conclusion is that non-us citizens commit a disproportionate amount of non-immigration crimes as well. Arguably THOSE stats are skewed, but it's not quite as bad as the sensational headline would have you believe.