glance over vs investigate

glance over

verb
  • to quickly inspect something (newspaper, notes) with the eyes 

investigate

verb
  • To examine, look into, or scrutinize in order to discover something hidden or secret. 

  • To inquire into or study in order to ascertain facts or information. 

  • To conduct an inquiry or examination. 

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