proliferate vs widen

proliferate

verb
  • To increase in number or spread rapidly; to multiply. 

widen

verb
  • To become wide or wider. 

  • To make wide or wider. 

  • To convert to a data type that can hold a larger number of distinct values. 

  • To broaden or extend in scope or range. 

  • To let out clothes to a larger size. 

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