Sparql endpoint/Maintenance

Find all event series all/most of whose events have less than N properties?
PREFIX rdf:  PREFIX rdfs:  PREFIX smwont:  PREFIX property: 

SELECT ?series (COUNT(DISTINCT ?event) AS ?eventCount) (SUM(?propertyCount) as ?propertySum) ((?propertySum / ?eventCount) AS ?avgPropPerEvt) WHERE { ?event property:Event_in_series ?series. { SELECT ?event (COUNT(DISTINCT ?p) AS ?propertyCount) WHERE { ?event a smwont:ConferenceEvent. ?event ?p ?o. } GROUP BY ?event ?series } } GROUP BY ?series HAVING (?avgPropPerEvt < 25) ORDER BY (?avgPropPerEvt) LIMIT 10