In the regionals, only seven of the sixteen #1 seeds advanced to the super regionals.
The SEC had ten teams in the regionals and only two (Vandy and Old Miss) advanced.
The ACC had seven teams in the regionals and just two (Maryland and Virginia) advanced.
The B12 had five teams in and four (Texas, Texas Tech, TCU, and Okie St) advanced.
The Pac12 advanced just one of five teams (Stanford).
The Big West advanced just one of four teams (UCIrvine).
Those five conferences had 31 of the 64 teams and advanced ten.
The B12 did far better than any other conference and they represent 25% of the remaining 16 teams.