for that matter vs on top of

for that matter

prep
  • as far as that is concerned. 

on top of

prep
  • In addition to something else. 

  • Atop 

  • Fully informed about, and in control of, something; up to speed with. 

  • Very close to, in any orientation or in time. 

How often have the words for that matter and on top of occurred in a corpus of books? (source: Google Ngram Viewer )