You can only achieve % fragmentation if you disable system restore, hibernation and stop your anti-virus from creating log files!
Most of us do that.
Since there are 2 kinds of fragmentation (file & free space), it would be nice to also have any idea how long free space defrag is going to take, as well.
Currently, users may see 0% FILE fragmentation (& wonder why defrag takes so long), not realizing there is also FREE SPACE fragmentation.