Just an additional point, detailed results from last year's Australian census should be available in about April or May this year.
These censuses occur every 5 years, and completion of censuses in Australia are compulsory. The "religious affiliation" section of the census is not compulsory, but most people fill it out anyway.
In a post on another thread, I pointed out that the trend from the last 3 Aust censuses show lower growth than what Watchtower Yearbook publisher numbers for Australia suggest. It will be interesting to see if that trend continues.