Query: What is the population of the smallest canton?
Context: However, there are considerable differences between the individual cantons, most particularly in terms of population and geographical area. Their populations vary between 15,000 (Appenzell Innerrhoden) and 1,253,500 (Zürich), and their area between 37 km2 (14 sq mi) (Basel-Stadt) and 7,105 km2 (2,743 sq mi) (Graubünden). The Cantons comprise a total of 2,485 municipalities.