Sort:  

I'm using steemsql's TxTransfers table which includes all the transfer types. That being said, the savings transfers are a tiny fraction (few MB's) and rarely have any memos. Who uses savings anyways?

The advantage of savings transfers is that you can memo spam people for free, by starting a savings withdrawal of any amount of STEEM/SBD, and then immediately cancelling it. It still costs bandwidth, though.
It doesn't seem like many people are using this, though. (I do, though)

Shhhh don't give them ideas.