The United Nations World Tourism Organization claims that the substantial growth of tourism activity clearly marks tourism as one of the most remarkable economic and social phenomena of the past century. Their data for international arrivals shows an increase from 25 million in 1950 to some 806 million in 2005, an average annual growth rate of 6.5%, expanding to over 1.6 billion by 2020. The World Travel and Tourism Council expects travel and tourism to generate US$ 6,477.2 billion of economic activity or 10.3% of total world GDP, and 234 million jobs or 8.7% of total employment in 2006. International tourism receipts combined with passenger transport currently total more than US$ 575 billion - making tourism the world's number one export earn err, ahead of automotive products, chemicals, petroleum and food. This exceptional growth of tourism since World War II was driven by higher discretionary incomes, smaller family size, changing demographics, lower transportation costs, improved public health standards, infrastructure development, and hospitable environments for tourists.