Those aren’t the only changes that the two have seen in their lifetimes.
When Norman and Zita were born, in 1921 and 1922 respectively, New Zealand was home to about 1.25 million people - a quarter of today’s population.
Norman shared his birth year with Robert Muldoon and Prince Philip, and Zita was born in the same year as Doris Day and Judy Garland.
The headline news of the era included the invention of Vegemite, the opening of Tutankhamun’s tomb, and the first tuberculosis vaccinations being given.
While neither have graced the halls of Parliament or the silver screen, both are committed Kiwis who have always lived in New Zealand, and raised their families here.
Each had two daughters, and Norman now has thirteen great-grandchildren, the youngest of whom are 8 and 10 years old.
Their advice for reaching a century in age was all about clean living and taking care of yourself.
Norman put his longevity down to exercise and keeping away from bad habits.
“I’ve never drunk and never smoked,” he said.
“I always did lots of walking and long-distance swimming.”
Similarly, Zita said that keeping fit and active has helped her to stay well beyond her 100th birthday.
Ultimately, she said, it came down to taking pleasure in everything that the world had to offer and to “enjoy life”.