Air travelâand hence airportsâwill see the fastest growth in demand, because it is by far the most sensitive to income: a 1% increase in income per person leads to a 1.4% increase in the number of passengers travelling by air. The number of air passengers could jump by more than 350% in China and by 200% in India over the next decade. -------------------------------------------------- Too simple. These numbers (increase in income = increase in air travel) are based on what? A US theory/model? Where exactly will these people be traveling to?