serve to vs tend

serve to

tend

verb
  • To be likely, or probable to do something, or to have a certain habit or leaning. 

  • To accompany as an assistant or protector; to care for the wants of; to look after; to watch; to guard. 

  • To kindle; ignite; set on fire; light; inflame; burn. 

  • To look after (e.g. an ill person.) 

  • To contribute to or toward some outcome. 

  • To manage (an anchored vessel) when the tide turns, to prevent it from entangling the cable when swinging. 

  • To make a tender of; to offer or tender. 

  • To wait (upon), as attendants or servants; to serve; to attend. 

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