IN the developing world, East Asia stands alone as the most dramatic success story in curbing population growth. China, where more than 70 percent of all couples practice some form of contraception, is a large part of the reason. Indonesia, Malaysia, South Korea, Taiwan, and Singapore have also made strong progress, according to the United Nations Population Fund 1991 report.In Latin America, progress has been particularly noteworthy in Chile, Costa Rica, Colombia, and Mexico. Availability of private sector contraceptives to middle- and upper-income women is considered a major factor in lower-than-average fertility rates in such nations as Argentina and Venezuela. South Asia includes areas of promise and major problems. Sri Lanka, for instance, is considered a showcase example of how family-planning programs should work. The states of Kerala and Tamil Nadu in Southern India have made strong progress in lowering birth rates. Yet northern India, Pakistan, and Bangladesh have made few visible strides. India - with 18 million births a year - is still the top single contributor to world population growth. In Africa, the rapid growth threatens to outpace jobs, food, schools, and other resources. Africa's population has doubled in the last three decades and is expected to triple during the next three decades. Only about 4 percent of all African couples use contraceptives, though use is notably higher in such nations as Botswana, Mauritius, Tunisia, and Zimbabwe, according to UN officials. One promising sign in Africa is the view of education as equally important for men and women, though levels achieved rem ain low. Population growth rates in Eastern Europe have not been much higher than those in Western Europe. But as they leave Marxism, many Eastern European nations want to exchange policies that allowed abortion to ones that encourage contraceptives. The UN Population Fund recently announced a new national family-planning program in Albania. The hope is to raise the proportion of couples using contraceptives from the current 1 percent to 10 percent.