The information that you are looking for is “mean time between failures”. (MTBF). When you know it, you will know how long 95% of the devices will still be working. Five per cent will have failed in that time period. If the MTBF is 9500 hours, after that time 95% of the devices will still be working and 5% will have failed.
Intersting, I have never seen anyone actually doing this. Good to know though. My LCD is getting close to the 4 (or is it 5) year mark and I sometimes feel it is getting dimmer as well.
I might as well check out what my lightbulb would cost me and get some DIY action going.