I've spend an hour memorizing all this stuff to just make everything clear for me. Well then, what I have found out... there are 366 episodes in total. We are talking about first MEGAseason of Bleach here. So, out of 366 episodes only 200 are normal, the other 166 being fillers, making 45% of all show. Suprisingly, even Harribel's past episode was one.
Totally filler arcs are seasons four, five, eight, thirteen and fifteen. Here are the numbers of ALL filler episodes: 33 50 128-131 132-137 147-149 64-109 168-189 204-205 213-214 227-229 230-265 284 287 298-299 303-305 311-316 317-342 355
The only seasons without fillers are first, eighth and eleventh. End of sixth and beginning of seventh seasons are both filler. Twelfth season is the only one to begin and end with fillers, and is followed by Zanpakuto filler arc as well. Fourtheenth season is the only one to be set between two filler arcs.