Sex ratio is used to describe the ratio of females to males in a population. In India, the sex ratio has been estimated via a number of methods and data sets including the decennial censuses, the National Family Health Surveys (NFHS), the Civil Registration System, the Sample Registration System and the Health Management Information System. In 2014, the ratio of female births per 1000 male births varied from 887 to 918 using these estimates. According to the NFHS-4 (2015–16) sex ratio of the total population was 991.