If you are sincere in your question, I can earnestly supply an answer for you.

The Scots and Irish were similar to each other. The Irish have a high number of emigrants living, working,owning, bars and restaurants here in the US, and generally left the customary 15% gratuity. The Scots,always lovely people,come in less numbers, but like the Irish, ultimately on average(65% for tipping), would leave the customary gratuity. The Welsh and Manx honestly were never in our records as having dined there. Yes, we kept records through a system of cards we would attach to the checks explaining the custom of gratuities, and asked whether or not we should include the gratuity for them. We also were required to get their country as well(always through polite conversation of course!)- this helped us to better assess where our customer base was largest and we could better focus our attention for other means,such as advertising on airplanes and magazines. This assesment is a matter of statistics and ten years of experience in the industry, nothing more,nothing less.