.... Yeah, that is an interesting stat. We do have what we thought would have been a headwind of simple demographics. Meaning much of the non-participation could be boomers retiring - so happily voluntarily. I imagine all western/westernized nations are having that issue with fewer babies and more retiring.
And of course the rate is based on the fiction that America has 320 million people those working all working legally with a SSN. Factor in all the illegals and the participation rate is likely higher.
But not much has changed demographically in the year + figure. That Stat was used as a bat in 14-16, yet is hardly mentioned now.