The real problem is that the rate of decline in joblessness slows during the rest of the economic expansion. The annual post-war pace of decline in unemployment during these periods has been reasonably uniform, the median being 0.5 percent a year.
If that pattern persists, the U.S. economy needs to keep expanding without interruption until 2020 for unemployment to fall to its pre-recession low of 4.4 percent. Should the next recession arrive earlier, as we suspect, it will take much longer. The implications constitute nothing short of a wake-up call for policy makers who promise to get job growth back on track.
Analysis: Good News On Jobs, But Will It Last? : NPR