- The sex ratio is defined as the number of females per 1000 males. A sex ratio above 1000 indicates a higher number of females than males. - Kerala's sex ratio has been above 1000 in several censuses, including the 1991 (1036) and 2001 (1058) censuses, which are likely candidates for the "last census" referred to when this question was framed. - Tamil Nadu, Karnataka, and Himachal Pradesh have sex ratios below 1000, meaning they have more males than females, although their ratios might be higher than the national average or other states.