Up until the early 20s, males outnumber females. This is because there are slightly more boy babies born than girl babies. However, beyond this age the pattern reverses and females outnumber males. The excess of females becomes very marked among those aged 65 years and over. This reflects the higher mortality rates amongst males and the longer life expectancy of females.
Latest estimates indicate that New Zealand's population continues to age.
Half of New Zealand's population is now over 34.6 years of age, compared with a median age of 31.3 years in 1991 and 25.7 years in 1971. The median age from 1991 onwards is based on the resident population concept. Figures prior to 1991 are based on the de facto population concept. People aged 65 years and over currently make up 12 percent of all New Zealanders, while children aged under 15 years now make up 23 percent of New Zealand's population. Over the last 20 years, the number of children has increased by three percent.