The latest ELT system data we have (
Cospas-Sarnat) is for calendar year 2013:
From January 2013 to December 2013, the system assisted in rescuing 2,156 persons in 720 SAR events (aviation, maritime & land).
In approx. 175 of those events, the Cospas-Sarnat system provided the only alert.
For the year, there were 153 aviation SAR events with 348 persons rescued.
For those interested, here's an interesting
Synopsis of a Real ELT Incident, involving a Bell 206B tour flight which crashed in very rugged terrain in Alberta, Canada.
The 406 MHz ELT provided the first and only alert that an accident occurred. MEO satellites detected the crash within 4 minutes, and LEO satellites computed the crash location and sent an alert within 80 minutes of the crash. Subsequently a second helicopter was dispatched and was able to find the wreckage within the hour. All four tourists were rescued; the pilot unfortunately succumbed to his injuries later on that day.