The U.S. official unemployment rate decreased slightly last month to 8.8 percent as the U.S. economy added 216,000 jobs. While the Obama administration praised the new job numbers, many economists point out that the recent drop in the unemployment rate is largely due to people leaving the labor force. Over the past 18 months, the unemployment rate has fallen from 10.1 percent to 8.8 percent. But during that same period, the labor force participation ratio, which measures the share of the U.S. population that has a job, has not changed.