CBO Paper: Global Population Aging in the 21st Century and Its Economic Implications [open pdf - 464KB]
"This paper, requested by the Chairman and Ranking Member of the Senate Finance Committee, is part of a series of reports by the Congressional Budget Office (CBO) that presents facts and research on immigration. It describes historical and projected population trends in different regions of the world and discusses current research on the international economic implications of those trends. Such information will help inform CBO's projections of the domestic and international economies and of the federal budget. In keeping with CBO's mandate to provide objective, nonpartisan analysis, this paper makes no recommendations."
Congressional Budget Office: http://www.cbo.gov/