So for the record, here is the GAO report:

and here is what was actually said:

federal jury administrator in one U.S. district court estimated that 1 to

3 percent of the people out of a jury pool of 30,000 over 2 years (about

300 to 900 people) said they were not U.S. citizens;

(page 42)

Again this is the opinion of one federal jury administrator, not the findings of a study. It is imperative that people dig through claims on the rumor mill critically.