Survey of Income and Program Participation: Dynamics of Economic Well-Being 2009-2012 Detailed Tables Release Number: CB14-TPS.82: “This table package traces a sample of U.S. residents and examines how many of them were poor during at least some portion of the four-year period as well as how long their poverty spells lasted. It also looks at how many entered into poverty, how many exited and how many stayed poor during the entire period. The statistics — which come from the Survey of Income and Program Participation — are presented at the national level by various demographic and socio-economic characteristics.”