The reasons that France tops the list are geographical and economic. The Europeans take most holidays abroad and France takes a large slice of that market, with bost the cultural delights of Paris and the big cities as well as the sun drenched coastal regions. Military enthusiasts also flock to the Normandy beaches.
Spain gets tourists seeking budget beach holidays. In recent years they have been joined by a more afflient traveller seeking cultural city breaks.
Many of Americas visitors head for Florida, but New York and California also do well from tourism from abroad. American border security over the last decade has somewhat limited the tourist trade.
The glories of the past are what brings many visitors to both Italy and the United Kingdom. Italy with its fine weather attracts more visitors, but the UK has the allure of Monarchy when the weather is less than clement.
China was closed to tourism until very recently, but with the upcoming Beijing Olympic games the Chinese are welcoming visitors in vast numbers. This is such a massive country that visitors will be spoiled for choice when it comes to deciding what to do.