Requirements for Multi-Discipline Cards

When looking at the requirements of multi-discipline cards (i.e. those cards that require two discipline simultaneously) in VtES I observed a certain tendency toward certain disciplines. To confirm my suspicion I compiled the following statistics:
As you can see, the single-clan discipline (and the few bloodline disciplines) lag a little bit behind the other disciplines as expected. What's quite surprising is the large number of multi-discipline cards which require Auspex. Actually, out of 41 multi-discipline cards there are 21 cards that require Auspex.

The statistics are based on all expansions up and including "Ebony Kingdom".