Could someone please tell me how on the KC site I could find out - if possible - how many litters a breeder has had in a year?  Thank you.

It's not possible.

It isn't possible to see that information

Does it have to be via the website?  Wouldn't the BRS be of help?

if you can mention the group the breed belongs to, perhaps someone will have copies of the previous years BRS and will be willing to help you out.

BRS = Breed Record Supplement. These can be bought from the Kennel Club, either a whole years worth (4 quarterly publications) or individually. You can buy older ones too, so don't need to limit yourself to the most recent ones. They are put in group order, and the breeds are in alphabetical order so easy to follow.

What group are you looking for? Someone on here may be able to help you.