All N02 readings for all sensors over a given time period

SELECT ?sensor, MAX(?DAY), MAX(?hour), AVG(?observationValue), MAX(?observationValue), MIN(?observationValue)
WHERE {
  GRAPH ?g {
    ?s <uri://opensheffield.org/properties#sensor> ?sensor .
    ?s a <http://purl.oclc.org/NET/ssnx/ssn#ObservationValue> .
    ?s <http://purl.oclc.org/NET/ssnx/ssn#endTime> ?observationTime.
    ?s <http://purl.oclc.org/NET/ssnx/ssn#hasValue> ?observationValue .
    ?sensor <http://purl.oclc.org/NET/ssnx/ssn#MeasurementProperty> <http://dbpedia.org/resource/NO2>     .
    BIND (bif:subseq( STR( ?observationTime ),0,11) AS ?DAY) .
    BIND (bif:subseq( STR( ?observationTime ),11,13) AS ?hour) .
    BIND (bif:subseq( STR( ?observationTime ),0,13) AS ?dayhour) .
    FILTER ( xsd:date(?observationTime) > xsd:date("2014-10-13") && xsd:date(?observationTime) <= xsd:date("2014-11-13") )
  }
}
GROUP BY ?sensor ?dayhour
ORDER BY ?dayhour ?sensor