It is very hard to tell. Not everyone who has looked for work in the last twelve months but is not now working is a ‘discouraged worker’. Some have gone to school, some have gotten married and decided to have a child instead, some have finagled their way onto SS disability and retired. There is definitely a group that has well and truly chucked working, either temporarily or permanently.
The workforce is always variable. Large numbers of women were drawn in during the 70s, who would in former decades have been housewives. During the 90s, guys were dropping out of college to become the CEO of web start-ups.
The real question is, what is the proper and correct percentage to have in the workforce in a healthy economy?
Who knows? According the the World Bank, the average Global labor participation rate was 65% in 2009. So that would imply that an average of 35% are not in the labor force, globally. But whose to say that's the proper ratio. There is no way to quantify that. The ratio is in the 50%'s in some countries, but it was 85% in Uganda in 2009.
I think that when Washington D.C. is borrowing $1.2 Trillion (plus) each year to keep an overly dependent society afloat, our labor participation rate is insufficient. That ought to be self-evident. So what should it be? Higher!