From 2000 to 2005, fewer than 5 percent of Americans used mass transit for their commutes, compared with about 50 percent in Japan and Europe. But that may be changing. More U.S. commuters than ever are taking buses, subways, or light rail to work instead of driving their cars. ... It’s not rocket science. For many, a roundtrip bus or metro fare is easier to stomach than gas prices that in some places have climbed to $4.79 per gallon. Three-quarters of Americans now believe more money should be spent on developing and improving mass transit systems, and cities are responding.