Thanks all for comments.
Smiddy: yes, that would be about right.
SBF:
I can't find any data for Unitarians. They don't seem to feature. Here is a quick self-explanatory table:
I included Bretheren because they concern me, because I come across them a bit.
Quick comments before I have to rush out the door:
Despite what the percentage growths suggest, I think SDA is doing better than JW, in that its demographics (ie no of young people) is far more in balance. JW was far better organised in dealing with the pandemic than most religions. There may also be an effect in recent numbers, that people are forgetting about what was revealed by an Aust Royal Commission of a few years ago. JW is doing better than most, for sure.
I will do a median age calc at some point when I get the time. I did a fertility calc for JW as a population, which gave a very low number, so I have to check it to see if I made a mistake.