Notes About The Data
The data comes from the Credit Suisse global wealth report 2018. This report is the best source for global wealth data.
The data from the global wealth databook is aggregated via this code and some basic calculations on the output.
Notable flaws in the data on this site
The main issue with the usage of the data is you cannot put people in brackets by wealth alone. Eg. Someone in debt in a third world country may not be one of the precariat, but one of the wealthy, but just heavily invested in some endeavor.
However, overall the generalizations made by level of wealth should be quite accurate and sufficient to draw conclusions from.