convo vs head-to-head

convo

verb

  • To have a conversation, to converse. 

noun

  • A conversation. 

head-to-head

adv

  • Directly, one-to-one. 

  • Facing one another. 

adj

  • Direct, one-to-one. 

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