Tourism is defined as travel for leisure or business purposes outside of one's usual environment for less than a year. The top 21 most visited cities globally are led by Paris, London, and Bangkok based on international visitor numbers from 2007-2008. Germany spends the most on international tourism at $91 billion in 2008, followed by the United States at $79.7 billion and the United Kingdom at $68.5 billion. International tourism saw a slowdown in growth in 2008 and declines in 2009 due to the global recession and H1N1 influenza outbreak.