According to the Romania's National Institute of Statistics (INSSE), Romania's total road network was estimated in 2015 at . The World Bank estimates the railway network at  of track, the fourth-largest railroad network in Europe. Romania's rail transport experienced a dramatic decline after 1989 and was estimated at 99 million passenger journeys in 2004, but has experienced a recent (2013) revival due to infrastructure improvements and partial privatisation of lines, accounting for 45% of all passenger and freight movements in the country. Bucharest Metro, the only underground railway system, was opened in 1979 and measures  with an average ridership in 2007 of 600,000 passengers during the workweek in the country. There are sixteen international commercial airports in service today. Over 12.8 million passengers flew through Bucharest's Henri Coandă International Airport in 2017.