PREFIX nmo: <http://nomisma.org/ontology#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?mintName (COUNT(?type) AS ?types) WHERE {
?type a nmo:TypeSeriesItem ; nmo:hasMint ?mint .
?mint rdfs:label ?mintName .
} GROUP BY ?mintName ORDER BY DESC(?types) LIMIT 15