The release of the June labor market data marks the third anniversary of the official end of the recession that began in June 2009. Thus, this is a good moment to look at the single best indicator of U.S. labor market health. As is so often the case, it is also one of the simplest: the employment-to-population ratio. In essence, this tells us what share of the working-age population (16-years old and above) has a job. When the ratio goes up, things are getting better. When it doesn’t, the labor market is not recovering. To know what kind of job...