hot shot vs workhorse

hot shot

noun
  • Round shot that has been heated to a glow before firing in order to set wooden enemy ships afire. 

workhorse

noun
  • Anyone or anything that does a lot of work; something or someone who works consistently or regularly. 

  • A horse used primarily for manual labor; a draft horse. 

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