However, the United Nations Population Fund’s (UNPF) study has highlighted that India will witness a longer duration of demographic dividend from 2005-06 till 2055-56. But the ‘boom’ of ‘demographic dividend’ is expected to remain restricted to selected states in different phases due to their varied population structures wherein, the Total Fertility Rate (TFR) is a key indicator of population growth. For instance, the 2017 Sample Registration Survey Report (SRS) shows that all southern and many western states already have a TFR of below 2.1, which is the tipping point wherein a population replaces itself. On the other hand, in underdeveloped states such as Jharkhand, Chhattisgarh, Madhya Pradesh, Rajasthan, Uttar Pradesh and Bihar, the TFR is still higher than 2.5. The UNPF study also confirmed that the opportunities for 'demographic dividend' have been closed in all the southern and western states like Kerala, Tamil Nadu, Delhi, Andhra Pradesh, Telangana, Gujarat, Punjab, West Bengal and Karnataka. In states like Odisha, Himachal Pradesh, Maharashtra, Jammu and Kashmir, Assam, Uttarakhand and Haryana, opportunities will be closed in the next few years. Benefits of ‘demographic dividend’ are likely to be seen only in few under-developed states such as Jharkhand, Chhattisgarh, Madhya Pradesh, Rajasthan, Uttar Pradesh, and Bihar.