Question: How much did the New York City Council Members give in 2015 for the Manhattan youth?
SPARQL:
 select sum(xsd:decimal(?amount)) as ?sum from <http://linkedspending.aksw.org/nyc-council-member-items> { ?obs qb:dataSet ls:nyc-council-member-items. ?obs lso:nyc-council-member-items-category <https://openspending.org/nyc-council-member-items/category/youth>. ?obs lso:nyc-council-member-items-borough <https://openspending.org/nyc-council-member-items/borough/manhattan>. ?obs lso:nyc-council-member-items-amount ?amount. }