human
Compute the average construction year for roads.
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 {
  ?road rdf:type :Road ;
        :hasConstructionYear ?year .
}
```