Segwit usage is still low. It is more likely that transaction volume has dropped because the crash scared a lot of people away.
Segwit usage is still barely at 10%, but I would say that it is very slowly going up.
I also doubt that this has a big effect on the current mempool size, probably some effect though...
Take a look at these charts of segwit usage:

Source:
http://segwit.party/charts/#But I don't think that was the point that OP was making, he's just happy that he's saving so much on fees.
You are right the segwit usage is only 11% at the movement but it is slowly going up and there is a reason for that to happen is coinbase gonna implement segwit soon,so I think it will help that percentage to increase a lot since most of the users uses coinbase as their bitcoin wallet.
But this is not happened due to the segwit,this is happening due to the empty memepool,but if all the users change to segwit then it will help the number of unconfirmed transctions under control for now if the price increases the more number of transaction also will increase will result back again what happened in December 2017.