passageway vs passthrough

passageway

noun
  • A covered walkway, between rooms or buildings. 

  • Any way for passing in, out or through something. 

passthrough

noun
  • A wall opening intended to allow something to be passed through it. 

  • as of a signal through a device or network. 

  • A legal entity intended to not incur (income) taxation at the entity, but solely at the beneficiaries. 

  • as of increased costs through a business entity to its customers through increased prices. 

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