Canon G15 vs. Lumix DMC-FZ200
In addition to Redfox88's comments ....
The FZ200's 80% is how well the FZ200 compares with the other cameras dpreview has tested with similar specs; i.e., same size sensor, zoom lens range, etc.
If you go to the "Conclusion" page of dpreview's FZ200 review where it has the box with the % for the various items, note the wording at the top:
If you use the "Include all catagories" be sure to hover your mouse pointer on the "i" to see the note: