Deadhead vs lament

Deadhead

noun
  • A fan of the rock band The Grateful Dead. 

lament

noun
  • A song expressing grief. 

  • An expression of grief, suffering, sadness or regret. 

verb
  • To express grief; to weep or wail; to mourn. 

  • To feel great sorrow or regret; to bewail. 

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