Australian population milestones - the significance of a number

This week the Australian population is set to hit 25 million.  Those of us who are interested in these things have been keeping a close eye on the ABS population clock as it approaches this milestone.  Every one minute and 23 seconds, another person is added to the population.  The ABS estimates that the 25 million milestone will be reached on the 7th August 2018.  In an environment where population has become a hot political topic, a number of other population milestones have been overlooked.  While 25 million people is a significant milestone, it's the dynamics of population change and where people live that inform planning policy.  For this reason, it's worth looking at other population milestones in Australia.