minus income earned by foreigners from domestic production.

_#_GNP/GDP methodology: In the Economy section, GNP/GDP dollar estimates for the OECD countries, the USSR, and the East European countries are derived from purchasing power parity (PPP) calculations rather than from conversions at official currency exchange rates. The PPP method normally involves the use of international dollar price weights, which are applied to the quantities of goods and services produced in a given economy. In addition to the lack of reliable data from the majority of countries, the statistician faces a major difficulty in specifying, identifying, and allowing for the quality of goods and services. The division of a PPP GNP/GDP estimate in dollars by the corresponding estimate in the local currency gives the PPP conversion rate. One thousand dollars will buy the same market basket of goods in the US as one thousand dollars, converted to the local currency at the PPP conversion rate, will buy in the other country. GNP/GDP estimates for the LDCs, on the other hand, are based on the conversion of GNP/GDP estimates in local currencies to dollars at the official currency exchange rates. One caution: the proportion of, say, defense expenditures as a percent of GNP/GDP in local currency accounts may differ substantially from the proportion when GNP/GDP accounts are expressed in PPP terms, as, for example, when an observer estimates the dollar level of Soviet or Japanese military expenditures; similar problems exist when components are expressed in dollars under currency exchange rate procedures. Finally, as academic research moves forward on the PPP method, we hope to convert all GNP/GDP estimates to this method in future editions of the Factbook.

_#_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 drugs legally produced and prescribed by doctors as well as those illegally produced and sold outside medical channels.

Cannabis (Cannabis sativa) is the common hemp plant, provides hallucinogens with some sedative properties, and includes marijuana (pot, Acapulco gold, grass, reefer), tetrahydrocannabinol (THC, Marinol), hashish (hash), and hashish oil (hash oil).

Coca (Erythroxylon coca) is a bush and the leaves contain the stimulant cocaine. Coca is not to be confused with cocoa which comes from cacao seeds and is used in making chocolate, cocoa, and cocoa butter.

Cocaine is a stimulant derived from the leaves of the coca bush.

Depressants (sedatives) are drugs that reduce tension and anxiety and include chloral hydrate, barbiturates (Amytal, Nembutal, Seconal, phenobarbital), benzodiazepines (Librium, Valium), methaqualone (Quaalude), glutethimide (Doriden), and others (Equanil, Placidyl, Valmid).

Drugs are any chemical substances that effect a physical, mental, emotional, or behavioral change in an individual.

Drug abuse is the use of any licit or illicit chemical substance that results in physical, mental, emotional, or behavioral impairment in an individual.

Hallucinogens are drugs that affect sensation, thinking, self-awareness, and emotion. Hallucinogens include LSD (acid, microdot), mescaline and peyote (mexc, buttons, cactus), amphetamine variants (PMA, STP, DOB), phencyclidine (PCP, angel dust, hog), phencyclidine analogues (PCE, PCPy, TCP), and others (psilocybin, psilocyn).

  Hashish is the resinous exudate of the cannabis or hemp plant
(Cannabis sativa).

Heroin is a semisynthetic derivative of morphine.

  Marijuana is the dried leaves of the cannabis or hemp plant
(Cannabis sativa).

Narcotics are drugs that relieve pain, often induce sleep, and refer to opium, opium derivatives, and synthetic substitutes. Natural narcotics include opium (paregoric, parepectolin), morphine (MS-Contin, Roxanol), codeine (Tylenol w/codeine, Empirin w/codeine, Robitussan A-C), and thebaine. Semisynthetic narcotics include heroin (horse, smack), and hydromorphone (Dilaudid). Synthetic narcotics include meperidine or Pethidine (Demerol, Mepergan), methadone (Dolophine, Methadose), and others (Darvon, Lomotil).

  Opium is the milky exudate of the incised, unripe seedpod of the
opium poppy.

  Opium poppy (Papaver somniferum) is the source for many natural and
semisynthetic narcotics.

  Poppy straw concentrate is the alkaloid derived from the mature dried
opium poppy.

  Qat (kat, khat) is a stimulant from the buds or leaves of Catha edulis
that is chewed or drunk as tea.

Stimulants are drugs that relieve mild depression, increase energy and activity, and include cocaine (coke, snow, crack), amphetamines (Desoxyn, Dexedrine), phenmetrazine (Preludin), methylphenidate (Ritalin), and others (Cylert, Sanorex, Tenuate).

_#_Infant mortality rate: The number of deaths to infants under one year of age in a given year per l,000 live births occurring in the same year.

_#_Land use: Human use of the land surface is categorized as arable land—land cultivated for crops that are replanted after each harvest (wheat, maize, rice); permanent crops—land cultivated for crops that are not replanted after each harvest (citrus, coffee, rubber); meadows and pastures—land permanently used for herbaceous forage crops; forest and woodland—land under dense or open stands of trees; and other—any land type not specifically mentioned above (urban areas, roads, desert). The percentage figure for irrigated refers to the portion of the entire amount of land area that is artificially supplied with water.

_#_Leaders: The chief of state is the titular leader of the country who represents the state at official and ceremonial funcions but is not involved with the day-to-day activities of the government. The head of government is the administrative leader who manages the day-to-day activities of the government. In the UK, the monarch is the chief of state and the prime minister is the head of government. In the US, the President is both the chief of state and the head of government.

_#_Life expectancy at birth: The average number of years to be lived by a group of people all born in the same year, if mortality at each age remains constant in the future.

_#_Literacy: There are no universal definitions and standards of literacy. Unless otherwise noted, all rates are based on the most common definition—the ability to read and write at a specified age. Detailing the standards that individual countries use to assess the ability to read and write is beyond the scope of this publication.

_#_Maps: All maps will be available only in the printed version for the foreseeable future.