railways carried 2,947 billion tonne-kilometers of freight and 961.23 billion Passenger-km, both traffic volumes are the highest in the world. The high volume of traffic that China's railway system carries makes it critical to its economy. Carrying some 24% of the world's railway transport volume on only 6% of the world's railways, the national rail system is modernizing and expanding rapidly and is efficiently within the limits of all available resources. China has the world's third largest rail network, as of 2010 it is 91,000 km (56,545 mi) long, an increase of some 5,000 km (3,107 mi) of track from 2009. About 47% of the network is electrified.