The Gini Coefficient measures the degree of inequality in a society. The higher it is, the greater the inequality. A Gini coefficient of 1 means that all income goes to 1 person; the rest receive zero. A Gini coefficient of 0 means income is exactly equally distributed. If you drew a Gini coefficient for wealth instead in income it would be much higher, i.e., significantly more unequal. I was surprised to see how high Oz's Gini coefficient is--the result of decades of neo-liberalism has changed my country from an egalitarian one to something much more unequal.
Disclaimer. After nearly 40 years managing money for some of the largest life offices and investment managers in the world, I think I have something to offer. These days I'm retired, and I can't by law give you advice. While I do make mistakes, I try hard to do my analysis thoroughly, and to make sure my data are correct (old habits die hard!) Also, don't ask me why I called it "Volewica". It's too late, now.
BTW, clicking on most charts will produce the original-sized, i.e., bigger version.