bis vs continually

bis

adv
  • Twice; showing that something is, or is to be, repeated, such as a passage of music, or an item in accounts. 

continually

adv
  • In a continual manner; non-stop. 

  • In regular or repeated succession; very often. 

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