The WTO's long-term forecast and assessment of the development of tourism up to the first 20 years, is called Tourism 2020 Vision.

An essential outcome of the Tourism 2020 Vision are quantitative forecasts covering a 25 years period, with 1995 as the base year and forecasts for 2000, 2010 and 2020.

Although the evolution of tourism in the last few years has been irregular, WTO maintains its long-term forecast for the moment. The underlying structural trends of the forecast are believed not to have significantly changed.

Experience shows that in the short term, periods of faster growth (1995, 1996, 2000) alternate with periods of slow growth (2001 and 2002). While the pace of growth till 2000 actually exceeded the Tourism 2020 Vision forecast, it is generally expected that the current slowdown will be compensated in the medium to long term.
 
WTO's Tourism 2020 Vision forecasts that international arrivals are expected to reach over 1.56 billion by the year 2020.

Of these worldwide arrivals in 2020, 1.2 billion will be intraregional and 0.4 billion will be long-haul travellers.

The total tourist arrivals by region shows that by 2020 the top three receiving regions will be Europe (717 million tourists), East Asia and the Pacific (397 million) and the Americas (282 million), followed by Africa, the Middle East and South Asia.

East Asia and the Pacific, South Asia, the Middle East and Africa are forecasted to record growth at rates of over 5 percent per year, compared to the world average of 4.1 per cent.

The more mature regions Europe and Americas are anticipated to show lower than average growth rates. Europe will maintain the highest share of world arrivals, although there will be a decline from 60 per cent in 1995 to 46 per cent in 2020. 

Long-haul travel worldwide will grow faster, at 5.4 per cent per year over the period 1995-2020, than intraregional travel, at 3.8 per cent.

Consequently the ratio between intraregional and long-haul travel will shift from around 82:18 in 1995 to close to 76:24 in 2020.

For more: http://www.world-tourism.org/facts/eng/publication.htm#5