occur vs spring to mind

occur

verb
  • To come or be presented to the mind; to suggest itself. 

  • To happen or take place. 

  • To present or offer itself. 

  • To be present or found. 

spring to mind

verb
  • To appear suddenly in one's thoughts, often as an example of something. 

How often have the words occur and spring to mind occurred in a corpus of books? (source: Google Ngram Viewer )