Private automobile ownership has grown rapidly in the 1990s; more than 1,000,000 cars were registered in Sofia after 2002. The city has the 4th-highest number of automobiles per capita in the European Union at 546.4 vehicles per 1,000 people. The municipality was known for minor and cosmetic repairs and many streets are in a poor condition. This is noticeably changing in the past years. There are different boulevards and streets in the city with a higher amount of traffic than others. These include Tsarigradsko shose, Cherni Vrah, Bulgaria, Slivnitsa and Todor Aleksandrov boulevards, as well as the city's ring road. Consequently, traffic and air pollution problems have become more severe and receive regular criticism in local media. The extension of the underground system is hoped to alleviate the city's immense traffic problems.