why the primary sector in India continues to be the largest employer in 1973 as well as in 2000?

There was change in the share of GDP of the three sectors but the primary sector continues to be the largest employer in 1973 as well as in 2000 due to the following factors:
(i) Enough jobs were not created in the secondary and tertiary sectors.
(ii) Industrial output or production of goods increased by eight times 1.e., from 6,000 crore to 50,000 crore approximately but the employment increased 2.5 times only.
(iii) Similarly in the tertiary sector, the production increased 11 times i.e., form 10,000 crore to 110,000 crore but employment increased only three times. Thus, the primary sector still employed about 63% people in the country.
(iv) There are more people in agriculture than is necessary. so even if some people are removed the production is not affected. Thus workers in agricultural sector are under- employed. It is also called disguised unemployment.