The United Nations is counting down the days till the "Day of Eight Billion."

The global population is expected to reach 8 billion on Nov. 15, according to the organization's data.

"Eight billion people, it is a momentous milestone for humanity," U.N. Population Fund chief Natalia Kanem said. "Yet, I realize this moment might not be celebrated by all. Some express concerns that our world is overpopulated. I am here to say clearly that the sheer number of human lives is not a cause for fear."

It took 12 years to grow from 7 to 8 billion and it will take about 15 years to reach 9 billion, according to the U.N.

The U.N. noted how the Earth's growth is due to, "the gradual increase in human lifespan owing to improvements in public health, nutrition, personal hygiene and medicine. It is also the result of high and persistent levels of fertility in some countries."

The top five most populated countries in the world are China, India, the United States, Indonesia, and Pakistan.

China and India both have populations in the billions. China has1,425,887,337 people and India has 1,417,173,173.

India will be the world's most populous country by 2023 and by about 2050 the population of India will be more than 1.66 billion, while the population of China will be 1.32 billion. China committed to a "one child" policy from 1980 to 2016.

The U.S. has a population of 338,289,857, while Indonesia has 275,501,339, according to a world population report. Pakistan has a population of 235,824,862.