India has made progress in terms of increasing the primary education attendance rate and expanding literacy to approximately three quarters of the population.[4] India's improved education system is often cited as one of the main contributors to the economic rise of India.[5] Much of the progress, especially in higher education and scientific research, has been credited to various public institutions. The private education market in India was 5%[citation needed] and in terms of value was estimated to be worth US$40 billion in 2008 but had increased to US$68–70 billion by 2012.[6]