I see the labor force participation rate [bls.gov] climb from 1970 to 1990, flat until 2007, then fall. That decline is a pretty recent thing...
If all you are doing is talking about population distribution in age ranges, you might want to re-think your argument.
In the US we have a nice population spike right at/after WWII, we call that the Baby Boomers. Born between 1940 and 1960, or so. And, hey, now in 2016 those people are between 56 and 76 years old. So your complaint about a falling labor force participation rate starting around 2007 is when the big Baby Boomer spike started hitting 65 years old.
Definition: The civilian labor force participation rate is the number of employed and unemployed but looking for a job as a percentage of the population aged 16 years and over. (definition from http://www.tradingeconomics.co...)
You're complaining that old people are not forced to work until they drop dead on the job.
This is really the argument you want to make?