I created this chart with the handy toolbox at the Bureau of Labor Statistics website, because there isn’t as much statistical obscurity involved in this particular ratio as I typically encounter in all the many measures of "unemployment." I chose the time-frame 1988-2009 to minimize distortion from demographic variations like large numbers of women entering the workforce from 1960-1980, for example.
Children under 16 aren’t included in the relevant population here, but otherwise it’s simple.
If the population (over 16) is 100, and 60 of them have jobs, then the employment-population ration is 60%.
At that topmost peak you see in April 2000, 64.7% of us Americans had jobs. Now 58.5% of us Americans have jobs.
Since the population of the United States is about 300,000,000 at this moment, and about 78% of them are 16 and over, the population 16 and over is about…
64.7% of the relevant population was employed in April, 2000, and 58.5% are employed now, representing a decrease of 6.2%.
If the same percentage of us were employed now as in April 2000, then 6.2% more of us would have jobs, and 6.2% of 234,000,000 is about…
14,400,000 missing jobs.
This calculation corresponds fairly closely with the figure of 15,000,000 unemployed Americans which Dean Baker employed in his column today.