That's roughly the same as the prison population,
"The study of 261 senior professionals in the United States found that 21 per cent had clinically significant levels of psychopathic traits. The rate of psychopathy in the general population is about one in a hundred."
I would guess that politicians are in the same range as the prisoners or higher, especially the more powerful politicians. Their puppeteers are probably much higher yet.
http://www.telegraph.co.uk/news/2016/09/13/1-in-5-ceos-are-psychopaths-australian-study-finds/Edited by JeffB at 12:58:23 on 09/14/16