voltage vs wattage

voltage

noun
  • The difference in electrostatic potential between two points in space, especially between live and neutral conductors or the earth. 

wattage

noun
  • The power requirement of some electric appliance. 

  • An amount or power (especially electric), expressed in watts, kilowatts etc. 

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