i vs y

i

character

  • The ninth letter of the English alphabet, called i and written in the Latin script. 

noun

  • The name of the Latin-script letter I/i. 

y

character

  • The twenty-fifth letter of the English alphabet, called wy or wye and written in the Latin script. 

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