ad libitum vs spontaneously

ad libitum

adj
  • Characterized by doing something ad libitum. 

adv
  • As much as desired, to one's fill, without restriction. 

spontaneously

adv
  • In a spontaneous manner; naturally; voluntarily. 

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