blue angel vs bluer

blue angel

noun
  • A blue flame produced by lighting one's flatus. 

  • A mollusc of genus Glaucus. 

bluer

noun
  • A blue blazer, part of the school uniform at Harrow School. 

  • Synonym of blue (“blue liquid added to laundry to prevent yellowing”) 

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