There’s plenty of anecdotal evidence that America’s workers are being left behind. But now a group of researchers and economists have identified a key part of the problem — the kinds of jobs increasingly available to America’s workforce. And what they’ve found, as illustrated in a new U.S. Private Sector Job Quality Index (JQI), is troubling. The Hill reports:

Since 1990, the United States has been creating an overabundance of low-quality service jobs. In fact, 63 percent of the production and nonsupervisory jobs created over the past 30 years have been in low-wage and low-hour positions. That’s a marked contrast from the start of the 1990s, when almost half of these jobs (47 percent) were high-wage.

For more than a year, economists from Cornell University, the Coalition for a Prosperous America, the University of Missouri, Kansas City and the Global Institute for Sustainable Prosperity have been sifting through private sector jobs data to develop the JQI. And they’ve found that, in the past three decades, the U.S. economy has become increasingly dependent on jobs that offer fewer hours of work and at lower relative wages.

What exactly do these low-hour, low-wage positions look like? They could be one of the almost 15 million nonmanagement jobs in leisure and hospitality. These offer an average of 24.6 hours of work per week at $14.65 an hour. That’s $360 a week.  Or they could be one of 13.5 million retail jobs offering 30.3 hours a week at $16.73 an hour. That’s $506 weekly.  

There are now roughly 105 million production and nonsupervisory jobs in the U.S. That’s 83 percent of all private sector jobs. And more than half of them — 58 million — pay less than the average weekly U.S. wage of $793. Many of these jobs don’t offer health care or other benefits. These are the best jobs that many Americans can find and the most hours they can get.