The Executive Summary of the International Energy Agency's (IEA) new edition of the Medium-Term Gas Market Report (MTGMR), for 2013. The new report predicts natural gas' piece of the worldwide energy picture will grow 2.4% from now until 2018. Growth in the U.S. continues rapidly. The report also says natural gas use in the transportation sector is about to rapidly increase around the world, thanks to U.S. shale gas.