Residential LED lighting: How much do they fade with age?

[cvanc]

Are my eyes deceiving me or are the LEDs I installed in my house about a year ago not as bright as they used to be?

I remember early LEDs had "fade as they age" issues.  Is there still some of that to be expected?  Are general trends known & quantified (i.e. 15% loss after 1,000 hours, or something like that)?

Thanks.

[coppice]

A lot of early domestic lighting LEDs faded quite rapidly. Just a few months operation was often enough to see obvious fading. These days they seem to have largely overcome this issue. All LEDs, from the earliest red ones, fade slowly with time, but as long as they are kept within their specified temperature range the process should be very slow.