John Smith is correct. Time before failure depends on total use time. Remember, when installing the new lamp to wash hands first to remove all traces of skin oil. Handle the lamp using a paper towel and place in socket. Wipe glass surface of bulb with paper towel to remove any trace oils.
For those who want to know:
You do this to prevent premature lamp failure. These lamps generate a lot of heat and any skin oils left on lamp surface will insulate and keep the heat from dissipating properly leading to filament destruction.
Wes |