found vs unaccounted for

found

noun
  • A thin, single-cut file for comb-makers. 

verb
  • To form by melting a metal and pouring it into a mould; to cast. 

  • To melt, especially of metal in an industrial setting. 

  • To begin building. 

  • To start (an institution or organization). 

unaccounted for

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