Here's all the devirtualizations from season 4, and the stats are as follows:
Yumi: 16
Ulrich: 15
Odd: 10
William: 10
Aelita: 7
Too bad for Yumi, she's my favorite character.
It seems that Yumi's been taking first place in the amount of devirtualizations sustained in every season (I skipped season 3 for now because I don't have all the episodes saved for editing, but I will get to it very soon)