PREFIX schema: <http://qweb.cs.aau.dk/airbase/schema/>
PREFIX property: <http://qweb.cs.aau.dk/airbase/property/> 
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT ?yn (max(?o3) as ?maxo3) WHERE { 
	?s property:type ?b . 
	?s property:ozoneClassification ?class . 
	?obs schema:station ?s . 
	?obs schema:O3 ?o3 . 
	?obs schema:year ?year . 
	?year property:yearNum ?yn . 
    ?obs schema:sensor ?sensor .
    ?sensor property:statisticShortName "Max"^^xsd:string . 
	FILTER(?b = "Background"^^xsd:string && ?class in ("suburban"^^xsd:string, "urban"^^xsd:string) && ?yn >= 2000 && ?yn <= 2014) 
} GROUP BY ?yn