shoot a line vs understate

shoot a line

understate

verb
  • To state (something) with a lack of emphasis, in order to express irony. 

  • To state (something) with less completeness than needed; to minimise or downplay. 

  • To state a quantity that is too low. 

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