UNITED NATIONS — India's population is expected to surpass China's in about seven years and Nigeria is projected to overtake the United States and become the third most populous country in the world shortly before 2050, a U.N. report said Wednesday.

The report by the Department of Economic and Social Affairs' Population Division forecasts that the current world population of nearly 7.6 billion will increase to 8.6 billion by 2030, 9.8 billion in 2050 and 11.2 billion in 2100.

People crowd a street in Lagos, Nigeria, on Dec. 23, 2016. Akintunde Akinleye / Reuters

It said roughly 83 million people are added to the world's population every year and the upward trend is expected to continue even with a continuing decline in fertility rates, which have fallen steadily since the 1960s.

"The population in Africa is notable for its rapid rate of growth, and it is anticipated that over half of global population growth between now and 2050 will take place in that region," said John Wilmoth, who is the population division's director. "At the other extreme, it is expected that the population of Europe will, in fact, decline somewhat in the coming decades."

The U.N. agency forecasts that from now through 2050 half the world's population growth will be concentrated in just nine countries — India, Nigeria, Congo, Pakistan, Ethiopia, Tanzania, United States, Uganda and Indonesia. Those nations are listed in the order of their "expected contribution to total growth," the report said.

During the same period, it added, the populations of 26 African countries are expected to at least double.

Nigeria, currently the world's seventh largest country, has the fastest growing population of the 10 most populous countries worldwide, and the report projects it will surpass the U.S. shortly before mid-century.

The new projections also forecast that China, which currently has 1.4 billion inhabitants, will be replaced as the world's most populous country around 2024 by India, which now has 1.3 billion inhabitants.