How many {powerplant} are to/by {turboprop} ?
How many turboprop powerplants are there?
SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P516 wd:Q309027 }
SELECT (COUNT(?sub) AS ?subs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?sub .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P516> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q309027 .
} 

What is the number of turboprop powerplants?