you suddenly woke up one day and realized there is an 3% universe your head which meant your anger right now. You were curious and went outside to check if the others had them too. The hashiras had them too

Sanemi: anger at 57% "WHO TF WOKE ME UP?!"

Muichiro:: "My bad, you were snoring so loud I couldn't sleep...btw, what are these numbers?" his percentage is at 14%

Shinobu: "Ara ara~ Well I'm pretty sure these numbers are what your anger percentage is" percentage at 1%