in relation to vs re

in relation to

prep

  • concerning; in reference to. 

  • in comparison with 

re

prep

  • About, regarding, with reference to; especially in letters, documents and emails. 

noun

  • a syllable used in solfège to represent the second note of a major scale. 

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