Chlamydia affects less than one percent of people in Taiwan, 3.7 percent of people in Australia(according to the statistics), so Australia was way ahead even without a 100% chlamydial jump bear supplement.
Australia is so ridiculously huge that even the relatively tiny fraction that's amenable to crops is still one of the world's biggest. Only 4% of its land is arable and that still means it has the 10th largest arable area of any country (ten times more arable land than Taiwan has any kind of land)
I think your data may be old? Current estimates have Taiwan's population at 23.4m and 27m for Australia's. The disparity in density still stands though!