It's a percentage rank, used a lot in many sports - here in Australia it's probably the most common way of splitting sides equal on wins because it balances offence against defence, which are both important parts of the contest (although to be fair if you can be defensive in your tougher games and blow out your easy ones it will favour that over sides that simply defend well). Your defence is worse than the other sides (statistically based on who you have played) so you're marginally behind them on percentage.
Pandoras - 122.9%
ASPK - 121.8%
Stara Dama - 121.7%