Forget Coinbase!There is almost no volume.This exchange doesn't have any significance.
Use the known bigger exchanges like Kraken, BitFinex, Bitstamp, BTCC etc as bases.
Or bitcoinaverage.com is also very good source.
That is not true. Today for example Coinbase has more volume than Bitstamp, Bitfinex or Kraken.
Source:
https://cryptowat.ch/