New Zealand's population today is concentrated to the north of the country, with around % of the population living in the North Island and % in the South Island as of . During the 20th century, New Zealand's population drifted north. In 1921, the country's median centre of population was located in the Tasman Sea west of Levin in Manawatū-Whanganui; by 2017, it had moved  north to near Kawhia in Waikato.