take a load off vs unlade

take a load off

verb
  • To go from a standing position to a sitting one. 

unlade

verb
  • To discharge a cargo; discharge a burden. 

  • To disburden; take the burden from; relieve. 

  • To discharge the cargo from. 

  • To unload. 

How often have the words take a load off and unlade occurred in a corpus of books? (source: Google Ngram Viewer )