as to vs re

as to

prep
  • With reference or regard to. 

  • According to; in a manner conforming or corresponding to; in proportion. 

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 as to and re occurred in a corpus of books? (source: Google Ngram Viewer )