p vs x

p

character
  • The sixteenth letter of the English alphabet, called pee and written in the Latin script. 

noun
  • proton 

x

character
  • The twenty-fourth letter of the English alphabet, called ex and written in the Latin script. 

  • Forming gender-neutral or otherwise more inclusive versions of words, especially Spanish-derived words by replacing both the masculine -o and feminine -a. 

conj
  • Used between the names of two characters to denote a ship, particularly in anime, manga, and video games. 

  • Used in place of and in artist collaborations. 

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