disburden vs unlade

disburden

verb
  • To rid of a burden; to free from a load carried; to unload. 

  • To free from a source of mental trouble. 

unlade

verb
  • To unload. 

  • To discharge a cargo; discharge a burden. 

  • To disburden; take the burden from; relieve. 

  • To discharge the cargo from. 

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