<Li> The remainder (those who have no job and have not looked for one in the last 4 weeks) are counted as "not in the labor force ." Many who are not in the labor force are going to school or are retired . Family responsibilities keep some others out of the labor force . </Li> <Li> "Marginally attached" workers are those not in the labor force because they have not searched for a job in the prior 4 weeks . However, they have searched in the prior 12 months and are both available for work and want to do so . Most marginally attached workers are not searching due to being discouraged over job prospects or due to being in school . </Li> <P> During the 1940s, the U.S Department of Labor, specifically the Bureau of Labor Statistics (BLS), began collecting employment information via monthly household surveys . Other data series are available back to 1912 . The unemployment rate has varied from as low as 1% during World War I to as high as 25% during the Great Depression . More recently, it reached peaks of 10.8% in November 1982 and 10.0% in October 2009 . Unemployment tends to rise during recessions and fall during expansions . From 1948 to 2015, unemployment averaged about 5.8% . There is always some unemployment, with persons changing jobs and new entrants to the labor force searching for jobs . This is referred to as frictional unemployment . For this reason, the Federal Reserve targets the natural rate of unemployment or NAIRU, which was around 5% in 2015 . A rate of unemployment below this level would be consistent with rising inflation in theory, as a shortage of workers would bid wages (and thus prices) upward . </P> <P> Various sources summarize the number of jobs created by Presidential term . The figures may include private or public job creation or combination . The Federal Reserve Economic Data (FRED) database contains the total nonfarm employment level, a measure of private sector job creation . For President Obama, between February 2009 and December 2015, the private sector added a total of 10 million jobs . The Calculated Risk blog also reported the number of private sector jobs created by Presidential term . Over 10 million jobs were created in each of President Clinton's two terms during the 1990s, by far the largest number among recent Presidents . President Reagan averaged over 7 million in each term during the 1980s, while George W. Bush had negative job creation in the 2000s . Each of these Presidents added net public sector (i.e., government) jobs, except President Obama . </P>

During the us great depression the unemployment rate peaked at