Sun vs Underground

Sun

name
  • An English tabloid newspaper. 

  • The star at the center of the Solar System (our solar system), which shines in our sky, represented in astronomy and astrology by ☉. 

  • The 91st sura (chapter) of the Qur'an. 

  • A surname. 

Underground

name
  • The London Underground. 

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