Question: What is the total number of office holders who preceded the people working under president bill clinton?
SPARQL query:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX prop: <http://dbpedia.org/property/>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT DISTINCT COUNT(?uri) WHERE { ?x prop:president <http://dbpedia.org/resource/Bill_Clinton> . ?uri prop:successor ?x  . ?uri rdf:type onto:OfficeHolder}