Private car ownership in Shanghai is rapidly increasing: in 2019, there were 3.40 million private cars in the city, a 12.5% increase from 2018. New private cars cannot be driven without a license plate, which are sold in monthly license plate auctions. Around 9,500 license plates are auctioned each month, and the average price is about () in 2019. According to the city's vehicle regulations introduced in June 2016, only locally registered residents and those who have paid social insurance or individual income taxes for over three years are eligible to be in the auction. The purpose of this policy is to limit the growth of automobile traffic and alleviate congestion.