A 2016 report published by New Zealand Statistics, has revealed that Tongans have the lowest home ownership in New Zealand compared to other Pacific Islander groups, Europeans and Maori. Home ownership rates among Asians and other groups were not compared in the report. 

The report stated that in 2013, Tongans had a home ownership rate of 15.3%, the lowest among Pacific Islanders. Tongans also had the biggest decline in home ownership, down from 33.9% in 2001. The Pacific Islander groups with the highest home ownership rates were Fijians (22.9%) and Samoans (19.2%). Pacific Islanders measured all together, had a home ownership rate of 18.5%. The home ownership rate is very low compared to Europeans (56.8%) and Maori (28.2%).

The report noted that the Pacific Islander population in New Zealand was significantly younger (median age: early 20's) in comparison to Europeans (median age: early 40's) but that if all groups were adjusted to the same age structure, Pacific Islanders would still have a low rate of home ownership (24.4%) in comparison to Europeans (54.6%) and Maori (35%).

The report suggested that lower income rates and higher unemployment rates among Pacific Islanders contributed to the low home ownership rate. 

Rising house prices was also emphasized. The report noted that house prices increased by close to 80% between 2002 and 2007, and that home ownership had declined among all groups since 2001. 

Source: http://www.stats.govt.nz/browse_for_stats/people_and_communities/housing/changing-maori-pacific-housing-tenure/home-ownership-patterns.aspx [2]