_id Year 1971 1981 1991 2001 2011 1 Total population (number) 11554983 15022839 18491097 23151423 26494504 2 Population distribution (percent) . . . . . 3 Residence . . . . . 4 Rural 96 93 91 86 83 5 Urban 4 7 9 14 17 6 Ecological belt . . . . . 7 Mountain 9.9 8.7 7.8 7.3 6.7 8 Hill 52.5 47.7 45.5 44.3 43 9 Terai 37.6 43.6 46.7 48.4 50.3 10 Development region . . . . . 11 Eastern 24 24 24 23 21.9 12 Central 33 33 34 35 36.4 13 Western 21 21 20 20 18.6 14 Mid-western 13 13 13 13 13.4 15 Far western 9 9 9 9 9.6 16 Total 100 100 100 100 100 17 Population composition by sex . . . . . 18 Male 50.3 51.2 49.9 49.9 48.5 19 Female 49.7 48.8 50.1 50.1 51.5 20 Sex ratio 101.4 105 99.5 99.8 94.2