In 1990, the U.S.-Irish bilateral agreement was changed to allow Irish airlines to serve Los Angeles and additional U.S. airlines to serve Dublin via Shannon. An amendment in 1993 allowed airlines to provide direct transatlantic services to Dublin, but 50% of transatlantic flights had to either originate or stop over in Shannon. During the 1990s, the airport began to struggle. However, 1996 saw the beginning of Continental Airlines flying between Dublin, Shannon and Newark, New Jersey. Shannon began to rebound in the late 1990s with the success of the Irish economy, the improving situation in Northern Ireland and an influx of American tourists. By the end of the decade Shannon had passenger numbers of 2.2 million and in the year 2000, a new £40 million terminal extension was opened.