The year 1921 is a year of the great divide in the demographic history of India when mortality started to decline leading to acceleration in the rate of population growth.During the next three decades (1921-51) the rate of population growth continued at a level of over one per cent per annum.. High rate of birth and Low rate of deaths-High population growth (developing). 3. Low rate of birth and Low rate of deaths-Low population growth (developed). In a country like India, where the children are considered as assets, rate of birth tend to be high.