According to TRAC:
Data show that in the first 9 months of FY 2006, federal prosecutors have rejected 87% of the FBI’s referrals on international terrorism. The report also shows that despite across-the-board staffing increases in the last few years, FBI investigations of all kinds have consistently resulted in fewer federal prosecutions. Detailed graphs and tables reveal how FBI staffing and enforcement priorities have been constantly changing since 1986. District-by-district FBI enforcement counts are updated through the end of FY 2005.