People moving to New Zealand to work and live continue to be the main driver behind the nation’s rising population, edging towards five million, the latest official figures show.

As of the end of June 2018 the country’s population was 4,885,300, which is the equivalent of adding the population of the Waikato region since 2013, according to the data published by Statistics New Zealand.

‘Net migration has been the main driver of population growth in recent years, reaching a peak of 72,400 migrants in the July 2017 year,’ population insights senior manager Brooke Theyers said.

A breakdown of the figures show that the population grew 1.9% in the 12 months to June 2018, down slightly from 2.1% in the same month in 2017. But Theyers pointed out that these growth rates are high by historical standards and compare with the latest growth rates of 1.6% for Australia and 1.2% for the global population.

The decline was mainly driven by an increase in migrant departures. Migrant arrivals and births were both down slightly, but overall New Zealand’s population is growing in most age groups, with the latest estimates showing more women than men are aged over 30. In contrast, men outnumber women at all ages under 30 years.

The balance of males to females ranges from 14,600 more males than females in the 20 to 24 year age group, to 14,000 more females than males at ages 45 to 49 age group.

‘The age-sex distribution is a result of a combination of drivers. These include international migration trends, sex ratios at birth, women generally living longer than men, and New Zealand’s ageing population,’ Theyers explained.

There are concerns being voiced about the impact of a growing population on infrastructure and key services such as health and education and about the population growing older.

People aged 65 years and older now make up 15% of the population in New Zealand compared with 12% some 20 years ago and it is projected to rise to around 23% within two decades. Already over 41% of towns and 29% of rural centres have more than 20% of their population aged 65 and over.

But not everyone who arrives is moving to Auckland, the data suggests. While the city has more than 1.65 million people, accounting for more than a third of New Zealand's population, growth is slowing.

Between June 2016 and June 2017, the city added 43,000 additional people, less than the 180,000 added between 2012 and 2017. However, Auckland's population could reach two million by as early as 2029 and hit 2.5 million by 2043, according to Statistics New Zealand medium range projections.