currency vs mintage

currency

noun
  • Money or other items used to facilitate transactions. 

  • The state of being current; general acceptance or recognition. 

  • Paper money. 

mintage

noun
  • The process of minting coins 

  • The batch of coins minted at one time 

  • The fee paid to a mint 

  • Coins collectively; specie 

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