Federal law requires the Administrative Office of the U.S. Courts to http://www.uscourts.gov/library/wiretap.html">report each year on law enforcement wiretapping activities which gives the public a sense of how often the government intercepts phone calls emails and other communications. Unfortunately there's no similar public reporting for the government's use of pen registers and trap and trace devices which record "routing" information rather than contents of communications. EFF has submitted several FOIA requests to try to document the frequency of this electronic surveillance in recent years.