p vs r

p

character

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

noun

  • proton 

r

character

  • The eighteenth letter of the English alphabet, called ar and written in the Latin script. 

verb

  • are (in text messaging and internet conversations) 

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