Ticking away
The moments that make up a dull day
You fritter and waste the hours
In an offhand way
Kicking around on a piece of ground
In your hometown
Waiting for someone
Or something to show you the way
Tired of lying in the sunshine
Staying home to watch the rain
You are young and life is long
And there is time to kill today
And then one day you find
Ten years have got behind you
No one told you when to run
You missed the starting gun
You don't think that 1980 chart has a very different shape? The current chart is almost flat from 20-60, while the 1980 chart is actually pyramid shaped, with the steepness is only slightly sharper past 60. And matches the steepness of the range from 25-50. Nobody talks about a 25-year-old die off.
You're better off charting the actuarial tables to convey the data you're trying to talk about (death rates), rather than relying on a stat that is influenced by birth rates and death rates in an opaque way.
That's the baby boom moving up the chart. It's 1980, they're 15-35. You can clearly see the normal population before the baby boom and it's fall off.