For sake of argument, let's say that coinbase keeps 100 small, hot wallets around. Every time coinbase rearranges funds in their wallets, they could create between 1 and infinity transactions. If, on average, they rearrange funds daily in such a way that 25 transactions occurs, they would account for 50% of your increase alone.

Given that all exchanges and processors routinely shuffle funds around, and every move is recorded as a transaction, you need exchanges (in total) to make 55 more transactions/day to make up your superduper exponential growth.

20K increase in transactions in bitcoin is no increase in transactions.