Richie (and others) - that 63.7% employment number also reflexts the number of RETIRED people.

Of course there will be more people not working than any time in the last 30 years - the huge demographic bubble known as the Baby Boomers is hitting retirement age (that's why the annual Social Security Surplus no longer exists).

The chart that Richie posted a link to doesn't break out the reasons WHY someone is no longer in the labor force. It simply refers to "non-institutional population"
(meaning not in prison or otherwise institutionalized from what I gather in context)