exchange of contracts vs trading

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. 

trading

noun
  • The carrying on of trade. 

adj
  • Carrying on trade or commerce; engaged in trade. 

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