Gaming revenues by state: State of the States: The AGA Survey of Casino Entertainment, American Gaming Association.
Prices of precious metals: cnbc.com
Total value of the worldwide virtual goods market: “Virtual goods revenue to hit $7.3 billion this year,” Bloomberg Business Week, November 15, 2010.
Total number of water bottles consumed: Beverage Marketing Corporation, www.beveragemarketing.com
Total sales of bottled water: Beverage Marketing Corporation, www.beveragemarketing.com
College and university enrollment: National Postsecondary Student Aid Study, U.S. Department of Education.