In a [comment][1] on "[Is it illegal to refuse US currency for a purchase?][2]", @[Dan Neely][3] said

> I don't think the main reason many businesses ban $50/100 bills is that they'd deplete their ability to make change for future customers. Minimizing losses from counterfeiters is the dominant concern.

Given the higher prevalence of $20 bills over $50 or $100 bills, I have always heard that the $20 is more frequently counterfeited in the US. 

Is this true?

[Gizmodo][4] makes a throw-away claim that the $100 is the most counterfeited but with no sources.


  [1]: https://skeptics.stackexchange.com/a/7702/637
  [2]: https://skeptics.stackexchange.com/q/7701/637
  [3]: https://skeptics.stackexchange.com/users/5878/dan-neely
  [4]: http://gizmodo.com/5521284/why-you-dont-want-to-counterfeit-the-hideous-new-100-bill