Edward I Newcastle Pennies, relative scarcity of Class 10?

[Coinery]

Does anyone have any insight into the relative scarcity of the three Newcastle classes, measured against themselves? 
 

Over the last 3 or 4 years I’ve managed to pick up a class 3 and a class 9 in good grades, but have struggled to find the class 10 in a similarly collectable grade, with the attached coin, bearing the full Edward legend, the best I’ve found to-date.

Edited 12 hours ago by Coinery

[Coinery]

The class 3 and 9 coins available in much better grades generally.

 

Edited 14 hours ago by Coinery

[TomGoodheart]

I have no idea, but it occurs to me that perhaps this is the sort of information that Martin Allen at the EMC might have to hand?
Mra25@cam.ac.uk