[Question] About the % number displayed

[ShadoUrufu]

This is more just a question rather than an issue. My vita battery icon looks full. It stopped charging. I've had the device at 100% at some point in the past few weeks, if I remember properly, though I may not. Currently it's at 72% and over the week, I've seen it hovering around 88%.

I'm just wondering if this means anything regarding the life of my battery. I usually keep the vita plugged while not in used, though it's always in sleep mode as I use it for the calendar setting and notifications. Or to take notes. I sometimes also use it to listen to music.

I'm just wondering if it's something I should be worried about.