Fewer workers, more aged

New Zealand's population will rise by nearly a million over the next 50 years, according to Statistics New Zealand projections released yesterday.

The population will reach 4.81 million by 2051, a rise of 930,000, or 24 per cent, from the June 2001 population of 3.88 million.

The figures assume New Zealand women will have, on average, 1.85 children - compared with a 2.1 average required for the population to sustain itself without immigration.

It also assumes that by 2051, life expectancy at birth will rise by six years and there will be net immigration of 5000 people a year from 2007 - the average annual migration for the past 100 years.

The age structure will change significantly by 2051. Half the population will be older than 45, compared with 35 per cent in 2001.

Higher migration levels will not markedly slow the average age, projections suggest. With a net migration gain of 20,000 a year, the median age in 2051 will be 43. Zero migration would give a median age of 46 years.

The number of people under 15 would fall from 880,000 in 2001 to 750,000 in 2051, a drop in the share of the population from 23 per cent to 16 per cent. Over-65s would rise from 460,000 to 1.22 million.

The working population - 15-64 years - is expected to fall after 2021, to 2.84 million by 2051.

- NZPA