Change in emissions of heavy metals and persistant organic pollutants

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX clrtap_nec_unfccc: <http://reference.eionet.europa.eu/clrtap_nec_unfccc/schema/>
PREFIX country: <http://reference.eionet.europa.eu/clrtap_nec_unfccc/country/>
PREFIX sector: <http://reference.eionet.europa.eu/clrtap_nec_unfccc/clrtap_nec_nfr09_sector/>

SELECT DISTINCT
#?clrtap
?country_label
#?year
?pollutant_name
?unit
round(((sum(xsd:double(?emissions_idx)) - sum(xsd:double(?emissions)))/((sum(xsd:double(?emissions_idx)) )))*-1000)/10.0 as ?change
sum(xsd:double(?emissions)) as ?emissions
sum(xsd:double(?emissions_idx)) as ?emissions_idx

WHERE {
  { 
    GRAPH <http://r.eionet.europa.eu/rdfdumps/clrtap_nec_unfccc/clrtap_nfr09_gf.rdf.gz> 
    {
      ?clrtap clrtap_nec_unfccc:country_code ?country_code .
      ?clrtap clrtap_nec_unfccc:pollutant_name ?pollutant_name .
      ?clrtap clrtap_nec_unfccc:sector_code ?sector_code .
      ?clrtap clrtap_nec_unfccc:unit ?unit .
      ?clrtap clrtap_nec_unfccc:year '2017' .
      ?clrtap clrtap_nec_unfccc:emissions ?emissions .

      _:clrtap_idx clrtap_nec_unfccc:country_code ?country_code .
      _:clrtap_idx clrtap_nec_unfccc:pollutant_name ?pollutant_name .
      _:clrtap_idx clrtap_nec_unfccc:sector_code ?sector_code .
      _:clrtap_idx clrtap_nec_unfccc:unit ?unit .
      _:clrtap_idx clrtap_nec_unfccc:year '1990' .
      _:clrtap_idx clrtap_nec_unfccc:emissions ?emissions_idx .

      FILTER (?sector_code = sector:NATIONAL_TOTAL)

      FILTER (?pollutant_name in ('Cd', 'Pb', 'Hg', 'HCB', 'PCB', 'dioxin', 'total PAH'))

    }
    ?country_code rdfs:label ?country_label .
  }
}
GROUP BY ?pollutant_name ?unit ?country_label ?year
HAVING sum(xsd:double(?emissions_idx)) > 0 
ORDER BY ?year ?pollutant_name