The religious composition of India’s population has undergone only modest changes since 1951, when the country conducted its first census as an independent nation, a study by Pew Research Center has found.

The study shows that between 1951 and 2011 when the last Census was conducted, the biggest rise came in the number of Muslims. They accounted for 9.8% of India’s population in 1951, while in 2011 they constituted 14.2%.

In the corresponding period, the population of Hindus declined by 4.3 percentage points to 79.8%.

The number of Christians, Sikhs, Buddhists and Jains remained almost the same in percentage terms.

(Source: Pew Research Center)

The population growth rate of all major religious groups in India have declined since 1951. However, the slowdown in growth rate has been more pronounced among religious minorities, who outpaced Hindus in earlier decades, the study showed.

For instance, between 1951 and 1961, the Muslim population expanded by 32.7%, 11 percentage points more than India’s overall rate of 21.6%. However, between 2001 and 2011, the difference in growth between Muslims (24.7%) and Indians overall (17.7%) was 7 percentage points.

The fertility rate has also declined among all religious groups. Fertility rate among Muslims still remains the highest, but it has dropped sharply from 4.4 children per woman in 1992 to 2.6 children in 2015, according to data from India’s National Family Health Survey.

According to the 2015 data, the fertility rate among Muslims is only 0.5 points higher than that in Hindus (2.1). In 1992, the fertility rate among Muslim women was 1.1 points higher than in Hindus.

(Source: Pew Research Center)

Migration and conversion have had little effect

The study also concluded that migration and religious conversion have had very little effect in altering India’s religious composition. These two factors along with fertility rate are the three main reasons which cause religious groups to shrink or expand, Pew Research Center said.

The study found that 98% of Indian adults still identify with the religion in which they were raised, thus showing the lack of impact of conversions on the religious composition.

Meanwhile, more than 99% of people who live in India were also born in India, the study found. This data showed that migration too has hardly had any impact.

In fact, the study found out that migrants leaving India outnumber immigrants three-to-one, and that religious minorities were more likely to leave than Hindus.