1992 INDIA SURVEY 
​Location: Mumbai and Chennai
Number of people interviewed: 265
1997 INDIA SURVEY
Location: Mumbai, Chennai, Delhi and Kolkata
​Number of people interviewed: 1003
2002 INDIA SURVEY
Location: Mumbai Chennai, Delhi Kolkata, Patna, Kochi
​Number of people interviewed: 1651​
2007 INDIA SURVEY 
​Location: Mumbai, Chennai, Delhi, Kolkata, Patna, Kochi,  Vijawada, Ahmedabad, Bhubhneshwar Ludhiana and Lucknow
​Number of people interviewed: 2475​
2012 INDIA SURVEY
​Location: Mumbai, Chennai, Delhi, Kolkata, Patna, Kochi,  Vijawada, Ahmedabad, Bhubhneshwar Ludhiana and Lucknow
​Number of people interviewed: 2459
2017 INDIA SURVEY 
​Location: Mumbai, Chennai, Delhi, Kolkata, Patna, Kochi,  Vijawada, Ahmedabad, Bhubhneshwar Ludhiana and Lucknow
​Number of people interviewed: 2510
In all WAS India surveys combined, 19 respondents reported ages under 18; the oldest respondent was 90 years old.