Once India's leading city, Kolkata experienced a steady economic decline in the decades following India's independence due to steep population increases and a rise in militant trade-unionism, which included frequent strikes that were backed by left-wing parties.[60] From the 1960s to the late 1990s, several factories were closed and businesses relocated.[60] The lack of capital and resources added to the depressed state of the city's economy and gave rise to an unwelcome sobriquet: the "dying city".[96] The city's fortunes improved after the Indian economy was liberalised in the 1990s and changes in economic policy were enacted by the West Bengal state government.[60] Recent estimates of the economy of Kolkata's metropolitan area have ranged from $150 to $250 billion (PPP GDP), and have ranked it third-most productive metro area of India.[97]