you can create 2 calculated fields to calculate counts for each type and put it in Tool tip.
Count of PR:
IF TYPE = "PR" THEN 1 ELSE 0 END
then bring SUM(Count of PR) in tool tip. This should work fine. same way you can do for CL.
Create separate calculated fields for each of your types.
If [Type] = 'CL' then 1 end
same for PR and any others
Now drag these calculated fields onto label mark and format within the tool tip box.
Create a calculated field to perform the count of type. You'll need to use a Level of Detail expression most likely - Overview: Level of Detail Expressions
Drag that new calculated field onto the Tooltip tab on the marks card and you'll be all set.
Thanks to all. That was a fast reply, and worked perfectly! So simple I feel silly for not thinking of it, but probably never would have come up with it on my own!