Between 2010-11 and 2015-16, student enrolment in government schools across 20 Indian states fell by 13 million, while private schools acquired 17.5 million new students, according to a new study that offers insights into India’s public-school education crisis.

Average enrolment in government schools–where teachers are paid, on average, salaries that are four times those in China–declined from 122 to 108 students per school over five years, while it rose from 202 to 208 in private schools, according to this March 2017 research paper by Geeta Gandhi Kingdon, professor of education and international development at the Institute of Education, London.

Yet, 65 percent of all school-going children in 20 states, about 113 million, continue to get their education from government schools, according to District Information System for Education (DISE) and education ministry data.

Why are students opting out of India’s government schools, which educate the poorest and most vulnerable students until the age of 14 for free, and migrating to fee-charging private institutions in such large numbers?

The study, which uses DISE data, traced this student migration to the belief among parents that private schools offer better value for money and better teaching than government schools. Multiple evaluations after controlling for students’ home backgrounds indicate that “children’s learning levels in private schools are no worse than, and in many studies better than, those in government schools”, said Gandhi.

Despite the Rs 1.16 lakh crore ($17.7 billion) spent on Sarva Shiksha Abhiyan (SSA)–the national programme for universal elementary education–the quality of learning declined between 2009 and 2014, IndiaSpend reported in March 2016.

Less than one in five elementary school teachers in India are trained, IndiaSpend reported in May 2015. In Delhi, India’s capital city and its richest state, by per capita income, half of all government-school teachers are hired on temporary contracts. These teachers are likely to be less motivated and accountable than teachers with full-time jobs, we reported in January 2017.