yes, that is true, but there is a more important reason.
1. technology, due to diverse technology needs to many companies all over the world, a greater percentage of the workforce needs to be allocated towards ICT.
2. More and more countries are spending more in education, and this more people can attain degrees, with which they can go for higher salary jobs, that usually are in the tertiary sector, for example engineers, and doctors.
3. automation, as can clearly be seen with toyota gretly reduces the need for workers, and thus the demand for primary workforce is decreasing and the demannd for tertiary is increaseing as explained in 1 and 2.