Dear student,
There has been a shift in the occupational structure in favour of secondary and tertiary sector because of the following factors:
a. In India, majority of the people are engaged in agriculture whose contribution to the economic development has been declining.
b. There are more people involved in agricultural / primary sector than actually required. Productivity per person is less, therefore their is a need to change.
c. Due to growing urbanisation, migration of people in cities has increased, thereby focus has shifted to secondary and tertiary sectors
d. Due to increase industrialisation demand for secondary and tertiary sector is increasing.
e. Growing demand for services like transportation, banking , insurance with increase in population requires a shift in occupational structure.