For a week ask customers you do not immediately recognise for the postcode of their home. Record this and map how far you pull people from to shop in your newsagency. Once you eliminate those in the area n vacation or passing through, such as grey nomads, you can soon get to an understanding of the geographic appeal of what you do. Map this and set a goal to increase your appeal, geographically.
This data will help you approach managing and marketing your business differently.