Can't speak for the US, but here in Germany there often aren't 12 monthly salaries to a year. Many people get a Christmas bonus and/or a summer bonus, but just as many don't. Personally, I get paid about 13 1/4 monthly salaries a year, so telling you my yearly salary would be more accurate than the monthly amount.
What are you on about? I've switched to LED bulbs about 10 years ago, and I've never had to replace a single one...