Today, tourism is the largest single industry on earth. In 2000, the "traveling population" reached 650 million, generating US $ 450 billion for the industry.
今天，旅遊已成全球最大產業，西元二○○○年時，旅遊人口衝破六億五千萬人次，為業者帶來四千五百億美元的營收。