Poverty in the United States is cyclical in nature with roughly 13 to 17% living below the federal poverty line at any given point in time, and roughly 40% falling below the poverty line at some point within a 10 year time span.^[2] Most Americans (58.5%) will spend at least one year below the poverty line at some point between ages 25 and 75.^[3] There remains some controversy over whether the official poverty threshold over- or understates poverty. http://upload.wikimedia.org/wikipedia/en/thumb/c/c9/Poverty_by_Age.png/400px-Poverty_by_Age.png 2008年底之前，中国政府确定的贫困线为人均年收入785元。该标准按照2005年的美元购买力平价约为人均每天0．57美元，而按照美元兑人民币现行汇率则只有人均每天0．31美元。这与世行推荐的人均1．25美元的贫困线相比，差距极为悬殊。 　　尽管中国政府刚刚宣布实施新的扶贫标准，将贫困线提高至人均年收入1196元，但世行的报告认为，这一新划定的贫困线依然偏低，并建议中国政府新增1546亿元投资，重建扶贫政策体系。