le, PPP estimates for developing
countries are often rough approximations. Most of the GDP estimates
are based on extrapolation of numbers published by the UN
International Comparison Program and by Professors Robert Summers and
Alan Heston of the University of Pennsylvania and their colleagues.
Currency exchange rates depend on a variety of international and
domestic financial forces that often have little relation to domestic
output. In developing countries with weak currencies the exchange rate
estimate of GDP in dollars is typically one-fourth to one-half the PPP
estimate. Furthermore, exchange rates may suddenly go up or down by
10% or more because of market forces or official fiat whereas real
output has remained unchanged. On 12 January 1994, for example, the 14
countries of the African Financial Community (whose currencies are
tied to the French franc) devalued their currencies by 50%. This move,
of course, did not cut the real output of these countries by half. One
important caution: the proportion of, say, defense expenditures as a
percentage of GDP in local currency accounts may differ substantially
from the proportion when GDP accounts are expressed in PPP terms, as,
for example, when an observer tries to estimate the dollar level of
Russian or Japanese military expenditures. Note: The numbers for GDP
and other economic data can not be chained together from successive
volumes of the Factbook because of changes in the US dollar measuring
rod, revisions of data by statistical agencies, use of new or
different sources of information, and changes in national statistical
methods and practices.

Gross domestic product (GDP): The value of all final goods and
services produced within a nation in a given year.

Gross national product (GNP): The value of all final goods and
services produced within a nation in a given year, plus income earned
abroad, minus income earned by foreigners from domestic production.

Gross world product (GWP): The aggregate value of all goods and
services produced worldwide in a given year.

Growth rate (population): The annual percent change in the population,
resulting from a surplus (or deficit) of births over deaths and the
balance of migrants entering and leaving a country. The rate may be
positive or negative.

Illicit drugs: There are five categories of illicit drugs - narcotics,
stimulants, depressants (sedatives), hallucinogens, and cannabis.
These categories include many drug