I like visualization of data. Numbers are fine but somehow, when you start figuring out ways to display numerica data non-numerically, you always end up with some additional insights.
I like this, The World's Economy Divided by Area, originally from HowMuch.
35 of the world's 196 countries make up 91% of the world's economy in terms of GDP. This, despite the title, is really about productivity and not wealth. The US, with about 4% of the world's population, produces 23% of the world's output. Not bad for a country that was a renegade upstart testing a new idea of governance just two centuries ago.
Here's another visualization that adds perspective. The Global Wealth Pyramid.
Finally, here's a depiction of the distribution of global wealth from Credit Suisse in "Snapshots of Global Wealth" (October 15, 2014). If you have more than $100,000 in wealth (and yes, your housing equity and your retirement account are included here), then you are sitting above the 90th percentile of the world wealth distribution. If you have more than $1,000,000 in wealth (or if you plan to end up at that level of wealth by the time you reach retirement age), you are in the 99th percentile of world wealth.Startlingly, an average middle-class American couple who attend a good college, works for forty years and saves 10-15% into a retirement account, don't divorce, buy and payoff the mortgage on a home, can anticipate, without extraordinary risk or effort, being in the global 1% by the time they retire. Now there's privilege for you.