India is forecast to surpass China to become the world's most populous country in 2023. Photo: Reuters

In 2022, China's population declined for the first time in 60 years, marking the beginning of a long period of population decline with profound impacts on China's and the world's economies. China's population of 1.4 billion is now slightly larger than India's 1.38 billion.

With 27.3% of the population between the ages of 15 and 29, India is one of the youngest countries in the world while China enters the aging population stage. The South Asian country's annual population growth rate has averaged 1.2% since 2011, down from 1.7% a decade ago.