Pennsylvania has how many american football teams?
SELECT DISTINCT COUNT(?uri) WHERE {?uri <http://dbpedia.org/property/city> <http://dbpedia.org/resource/Pennsylvania>  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/AmericanFootballTeam>}
Pennsylvania