The remaining 0.5 per cent of people identified as other identities, including either takatāpui, asexual and pansexual.
Stats NZ's general manager Jason Attewell said the new data highlights wellbeing disparities and will help the Government to better address some of the concerns.
When it comes to measuring overall life satisfaction, people who identified as bisexual were the least satisfied with life.
Stats NZ data showed that close to 8 out of 10 adults rated their overall life satisfaction at 7 out of 10 or higher.
But, on the same measure, just 6 out of 10 bisexual people rated their life satisfaction as a seven or above.
"The lower life satisfaction rating for people identifying as bisexual was reflected across a number of wellbeing measures," the report said.
For example, a third of people who identified as bisexual reported having poor mental wellbeing.
That compares to roughly a fifth of adults who reported having poor mental wellbeing.
Meanwhile, the data showed that people who identified as gay/lesbian or bisexual found it "significantly harder to express their identity than Kiwis who identified as heterosexual.
Some 74 per cent of gay/lesbian, and 70 per cent of bisexual people, found it "very easy" to express their identity.
That number is 85 per cent compared with heterosexual people.
Stats NZ officials say that the next GSS – which will be released in 2020 – will include statistics on gender identity and people's "sex at birth".
In terms of New Zealander's overall wellbeing, the majority of Kiwis – some 80 per cent – rated their life satisfaction highly, a 7 out of 10 or higher on the wellbeing scale.