exchange of contracts vs sales

exchange of contracts

noun
  • The act of exchanging contracts. 

  • The point or stage at which a conveyancing contract comes into existence between negotiating parties for the carrying out of a disposition of an estate in land; usually requiring the payment of a deposit. 

sales

noun
  • The activities involved in selling goods or services. 

  • The amount or value of goods and services sold. 

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