The world's population continues to grow. There now are about 4 billion of us on earth. That could reach 6 billion by the end of the 20th century and 11 billion in a 1 75 years. Experts have long been 2 about such a growth. Where will we find the food, water, jobs, houses, schools and health care for all these people? A major new study shows that the situation may be changing. A large and rapid 3 in the world's birth rate has taken place during the past 10 years. Families generally smaller now than they were a few years ago. It is happening in both developing and industrial nations. Researchers said that they found a number of reasons for this. More men and women are waiting longer to get married and are using birth control devices and methods to 4 or delay pregnancy. More women are going to school or working at jobs away from home instead of having children. And more governments, especially in developing nations, now support family planning programs to reduce population growth. China is one of the nations that have made great progress in reducing its population growth. China has already cut its rate of population growth by about one half since 1970. Each Chinese family is now 5 to have no more than one child. And the hope is to reach a zero population growth with the total number of births equaling the total number of deaths by the year 2000. Several nations in Europe already have fewer births than deaths. Experts said that these nations could face a serious shortage of workers in the future. And the persons who are working could face much higher taxes to help support the growing number of retired people.