unladen vs unleaded

unladen

adj

  • Not carrying anything; unburdened. 

unleaded

adj

  • Without lead. 

  • Containing no more than 0.05 grams of lead per gallon. 

  • Decaffeinated. 

  • Having low alcohol content. 

noun

  • Low-alcohol beer. 

  • An unleaded fuel. 

  • Decaffeinated coffee. 

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