clientele vs viewership

clientele

noun
  • The body or class of people who frequent an establishment or purchase a service, especially when considered as forming a more-or-less homogeneous group of clients in terms of values or habits. 

viewership

noun
  • collectively, the viewers of a television program or other video broadcast 

How often have the words clientele and viewership occurred in a corpus of books? (source: Google Ngram Viewer )