By the early 1950s the Tōkaidō Line had become the main transportation artery of Japan. Although it was only 3 percent of the railway system by length, it carried 24 percent of JNR's passenger traffic and 23 percent of its freight, and the rate of growth was higher than any other line in the country. By 1956 electrification was completed along the Tokyo-Osaka section and with the introduction of new "Kodama" trains, travel time was reduced to six and a half hours. The line became so popular that tickets regularly sold out within ten minutes of being put on sale, one month in advance of the travel date.