haha vs hehe

haha

intj
  • An onomatopoeic representation of laughter. 

noun
  • Type of boundary to a garden, pleasure-ground, or park, designed not to interrupt the view and to be invisible until closely approached. 

  • A large leafy Hawaiian plant, Gunnera petaloidea. 

verb
  • To laugh. 

hehe

intj
  • An approximation to the sound of a mischievous giggle. 

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