double entendre vs spoonerism

double entendre

noun
  • A phrase that has two meanings, especially where one is innocent and literal, the other risqué, bawdy, or ironic; an innuendo. 

spoonerism

noun
  • A play on words on a phrase in which the initial (usually consonantal) sounds of two or more of the main words are transposed. 

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