human
Calculate the average construction year for all construction.
gpt
```sparql
PREFIX :     <http://example.org/ontology#>
PREFIX rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

SELECT (AVG(?year) AS ?avgYear)
WHERE {
  ?c rdf:type :Construction ;
     :hasConstructionYear ?year .
}
```