Thanks for this change, it's helpful. I hope an option to sort by descending order is still on the todo list ;-)
This is a great addition!
Also, I'm not sure when it was added, but the "Average Progress" addition to the game sorting order is very appreciated too. (though I'm a little surprised it doesn't show the 100% games too - still a great feature nonetheless)
EDIT - It seems "Completion Date" also does this same progress sorting now too and does show the 100% games, so even better!
Strangely though, my progress on Rocket League is 99% as I have 1 achievement left to earn, but it does not show in the Average Progress list. It does appear at the top my Completion Date sorting though, at 99% and above the games with 100%. Maybe because it previously was at 100% until the game added more achievements?