An estimate is a figure for a time that has already passed. In Place Forecast, estimated figures appear to the left of the jump-off year on charts. They come from data the Australian Bureau of Statistics has put together. The word "estimated" does not mean a rough guess. It means the ABS has used the best data it has to work out the number. For example, the estimated resident population draws on Census counts, birth and death records, and migration data.
Figures to the right of the jump-off year are projections, not estimates.