it looks like 6 disk have been added to your aggregate without changing the default raidgroup size of 16 and so you ended up with this misbalanced configuration.
as of the Storage Subsystem Technical FAQ, the raid group sizes should not differ by more than one disk:
"Drive deficiencies should be distributed across RAID groups so that no single RAID group is deficient more than a single drive."
and if I remember correctly, the smaller raidgroup must have at least half the disk count of the bigger raidgroup. but I can't find a doc about that right now.
so I think your configuration is not even supported by Netapp.