freak out vs go mental

freak out

verb
  • To react with extreme anger or fear, to the extent that one loses one's composure or behaves irrationally. 

  • To scare or unnerve someone. 

go mental

verb
  • To become extremely angry. 

  • To become wild with excitement. 

How often have the words freak out and go mental occurred in a corpus of books? (source: Google Ngram Viewer )