solarize vs suntan

solarize

verb
  • To subject to solarization. 

  • To treat soil by covering with plastic and exposing to sunlight. 

  • To convert to using solar energy. 

suntan

verb
  • To obtain a suntan by exposure to ultraviolet light. 

  • To attempt to obtain a suntan. 

noun
  • In humans a brown or darkened coloration of the skin caused by exposure to ultraviolet light. 

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