Our Certification History is part of the details stored in our SB Account. I assume that it would be possible for one of the SB board members to compile this information for us all to learn.
I guess you could run a survey as to what is your top cert and list a half al dozen ow aow rescue nitrox master dm tech other
that should generate a good set of data atlaeeast form the SB members which is probably not the best set to represent the globe