Source: For fiscal years (FY) 1994–2005: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, State Library Agencies (Washington, DC: National Center for Education Statistics, 1996–2006). For FY 2007–2008: Institute of Museum and Library Services, State Library Agencies (Washington, DC: Institute of Museum and Library Services, 2007–2008). Publications for all years are downloadable from http://www.imls.gov/research/state_library_agency_survey.aspx. Amounts for FY 2009–2014 were calculated from public-use data posted at https://www.imls.gov/research-evaluation/data-collection/state-library-administrative-agency-survey/state-library-public, downloaded 6/24/2016.
Revenue figures were adjusted for inflation using the Gross Domestic Product Implicit Price Deflators produced by the U.S. Bureau of Commerce’s Bureau of Economic Analysis (downloaded from http://research.stlouisfed.org/fred2/series/GDPDEF/downloaddata).
Population data are from U.S. Census Bureau, “Annual Estimates of the Resident Population by Sex, Race, and Hispanic Origin for the United States: April 1, 2000 to July 1, 2009 (NC-EST2009-03),” https://www.census.gov/popest/data/national/asrh/2009/tables/NC-EST2009-03.xls; and U.S. Census Bureau, “Annual Estimates of the Resident Population for the United States, Regions, States, and Puerto Rico: April 1, 2010 to July 1, 2015 (NST-EST2015-01),” http://www.census.gov/popest/data/state/totals/2015/tables/NST-EST2015-01.xlsx.