| stats count by flag system
| xyseries flag system count
| fillnull value=0
| stats count by flag system
| xyseries flag system count
| fillnull value=0
thanks @ITWhisperer , but i'm not getting the value " 0 ".
so i would like to add more to your spl
| stats count by flag system
| xyseries flag system count
| fillnull value=0
Good point - updated response