Forbes 400: https://www.forbes.com/sites/forbespr/2018/10/03/forbes-releases-37th-annual-forbes-400-ranking-of-the-richest-americans/#6c9a1f4d5cb1
 Richest 400 Americans own $2,900 billion (minimum for entry to club is $2.1 billion)

Business Insider: https://www.businessinsider.com/how-many-billionaires-world-billionaires-2017-10
 560 billionaires in U.S.

GWD: http://publications.credit-suisse.com/index.cfm/publikationen-shop/research-institute/global-wealth-databook-2018-en/
 Table 3-6: 1,144 Americans with $500 million or more.
  In addition to Forbes 400, 744 have between $500 million and $2.1 billion:
   160 (560-400) between $1b and $2.1b, average $1.55b => $248 billion
   584 between $500m and $1b, avg $750 million => $438 billion
  19,253 Americans between $100 million and $500 million, average $300 million => $5,775 billion
  4,603 Americans close to $100 million => $450 billion

TOTAL: $2,900 + $248 + $438 + $5,775 + $440 => $9,801 billion

WORLD:
 GWD, Table 2-4
  $317 trillion total global wealth
 GWD, Tables 3-4 and 6-5
  Bottom 7 deciles own 3.1% of global wealth => $9,830 billion