Sources

All internet data accessed in October and November 2010, double-checked and verified in December 2010.

1. Niagara Falls flow rate sourced from http://www.niagaraparks.com/media/geology-facts-figures.html. Recommended daily water consumption sourced from the Mayo Clinic, available at http://www.mayoclinic.com/health/water/NU00283. Data estimates of people without access to safe drinking water sourced from the World Health Organization, available at http://www.who.int/water_sanitation_health/mdg1/en/index.html.

2. United States marriage data sourced from the US Center for Disease Control, available at http://www.cdc.gov/nchs/data/nvsr/nvsr58/nvsr58_25.pdf.

3. United States birth data sourced from the US Center for Disease Control, available at http://www.cdc.gov/nchs/data/nvsr/nvsr58/nvsr58_25.pdf. Birth data for India and China sourced from the US Central Intelligence Agency, available at https://www.cia.gov/library/publications/the-world-factbook/fields/2054.html.

4. Plane passenger and flight data sourced from the US Bureau of Transportation Statistics, available at http://www.bts.gov/press_releases/2010/bts015_10/html/bts015_10.html and http://www.transtats.bts.gov/Data_Elements.aspx?Data=2, respectively.

5. Solar energy impact rate sourced from EcoWorld.com, available at http://www.ecoworld.com/energy-fuels/how-much-solar-energy-hits-earth.html.

6. Text message statistics sourced from the CTIA, available at http://www.ctia.org/media/press/body.cfm/prid/1936.

7. Data based on the usage rate of a 100-watt incandescent lightbulb and the US Census Bureau estimate of the number of households, available at http://www.census.gov/population/projections/nation/hh-fam/table1n.txt.

8. New York City subway data sourced from http://www.ny.com/transportation/subways.

9. New bike sales data for 2009 sourced from the National Bicycle Dealers Association, available at http://nbda.com/articles/industry-overview-2009-pg34.html. 2006 and 2007 shoe sales data sourced from the American Apparel and Footwear Association, available at http://www.apparelandfootwear.org/statistics.asp.

10. Based on 2007 emissions data sourced from the UN Millenium Development Goals Indicators, available at http://mdgs.un.org/unsd/mdg/SeriesDetail.aspx?srid=749&crid=. 2007 population estimates for the United States sourced from the US Census Bureau, available at http://www.census.gov/popest/states/NST-ann-est2007.html.

11. Data extrapolated from sales milestones reached on 9/9/2009 and 2/24/2010, sourced from http://en.wikipedia.org/wiki/ITunes_Store#Market_share_and_milestones.