annex vs cojoin

annex

verb
  • To join; to be united. 

  • To attach or connect, as a consequence, condition, etc. 

  • To add something to another thing, especially territory; to incorporate. 

noun
  • An appendix to a book or document. 

  • An addition to the territory of a country or state, from a neighbouring country or state, normally by military force. 

  • An addition, an extension. 

  • An addition or extension to a building. 

cojoin

verb
  • To join together; to conjoin. 

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