Sources: Population from UN, World Population Prospects--The 2000 Revision (2001); historical GDP from N. Nakicenovic et al., Global Energy Perspectives,
Cambridge Press, 1998, p. 30, updated on the basis of information from US DOE, Energy Information Administration; historical energy estimate based on UN World
Bank and DOE/EIA data and checked against chart in Nakicenovic, p. 66. GDP and energy projections are discussed in accompanying text