Monthly distribution of the total number of arrivals and nights spent at tourist accommodation establishments

PREFIX sdmx-measure: <http://purl.org/linked-data/sdmx/2009/measure#> 
PREFIX sdmx-dimension: <http://purl.org/linked-data/sdmx/2009/dimension#> 
PREFIX sdmx-attribute: <http://purl.org/linked-data/sdmx/2009/attribute#> 
PREFIX property: <http://rdfdata.eionet.europa.eu/eurostat/property#> 
PREFIX geo: <http://dd.eionet.europa.eu/vocabulary/eurostat/geo/>
PREFIX unit: <http://dd.eionet.europa.eu/vocabulary/eurostat/unit/>
PREFIX indic_to: <http://dd.eionet.europa.eu/vocabulary/eurostat/indic_to/>
PREFIX nace_r2: <http://dd.eionet.europa.eu/vocabulary/eurostat/nace_r2/>

SELECT DISTINCT
month(?date) as ?date
round((sum(?obsValue)/12) / sum(?obsValue_year) *1000)/10.0 as ?obsValue

WHERE { 
 GRAPH <http://rdfdata.eionet.europa.eu/eurostat/data/tour_occ_nim.rdf.gz> {   
    _:tour_occ_nim sdmx-dimension:timePeriod ?date . 
    FILTER (year(?date) = 2015)
    _:tour_occ_nim sdmx-dimension:refArea geo:EU28 . 
    _:tour_occ_nim property:indic_to indic_to:B006 . 
    _:tour_occ_nim sdmx-attribute:unitMeasure unit:NR . 
    _:tour_occ_nim property:nace_r2 nace_r2:I551-I553 . 
    _:tour_occ_nim sdmx-measure:obsValue ?obsValue .

    _:tour_occ_nim_year sdmx-dimension:timePeriod ?date_year . 
    FILTER (year(?date_year) = 2015)
    _:tour_occ_nim_year sdmx-dimension:refArea geo:EU28 . 
    _:tour_occ_nim_year property:indic_to indic_to:B006 . 
    _:tour_occ_nim_year sdmx-attribute:unitMeasure unit:NR . 
    _:tour_occ_nim_year property:nace_r2 nace_r2:I551-I553 . 
    _:tour_occ_nim_year sdmx-measure:obsValue ?obsValue_year .
  }
}
ORDER BY month(?date)