How many {signatory} are to/by {Bill Clinton} ?
how many signatures are held by bill clinton?
SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P1891 wd:Q1124 }
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/P1891> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q1124 .
} 

Bill Clinton holds how many signatures?