It's Census Day and TVNZ1's Seven Sharp has been digging back through old Census data to find out how New Zealand's average Trev or Tracey has changed over time.

Kiwis have been doing the Census in some form or another since 1850.

Starting back at the 1871 census, the most "common" Kiwi was male, European, aged 21 to 40 and devoted to the Church of England.

Things stayed that way until 1951 when the average Kiwi was still European, still male, but thanks to the baby boom post World War Two, the average age was under five years old.

Forty-five years later, in 1996, the "average Joe" was now Josephine. Females outnumbered males. They were still European, but the average age is 33.

And the most common religion in 1996 was no religion at all - atheist

Not much changed when the last Census came round five years ago, we were just getting older.

In 2013 our average age was up to 44, still female, still European and still happy to say she's an atheist.