Authored in 2004, at which point Oprah had $1.1Bn[1]
[1] https://www.forbes.com/maserati/billionaires2004/LIRO0ZT.htm...
Edit: nvm, the article talks about a Chris Rock quote from the previous year (2003) at which point Oprah doesn't show up on the Forbes website.
Forbes says there are 1940 billionaires in the world today, that puts anyone over $1 billion in the top 0.0001 percent.