Question

How tertiary sector is growing so rapidy

Answer 1

Services use to show high income-elasticity. So, as income increases (and it is increasing worldwide but specially in emerging economies), the demand of services increases.

This income-elasticity emerges both in personal services (hair-dressers, dentists, lawyers) as in business services (nowadays the ouput of the manufacturing sector includes more and more services as design, quality controls, sophisticated financial schemes,....)

Hope to have been useful..