happen vs transpire

happen

verb
  • To occur or take place. 

  • To do or occur by chance or unexpectedly. 

  • To encounter by chance. 

transpire

verb
  • To happen, take place. 

  • Of plants, to give off water and waste products through the stomata. 

  • To become known; to escape from secrecy. 

  • To give off (vapour, waste matter etc.); to exhale (an odour etc.). 

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