query: SELECT
    (wd:Q2481549 as ?item) 
    ("year of publication" as ?xAxisTitle) 
    ("total pages published" as ?yAxisTitle)
    (GROUP_CONCAT(?year;separator=",") as ?x)
    (GROUP_CONCAT(?yeartotal;separator=",") as ?y)
    ("area" as ?type)
    ("200" as ?height) 
    ("600" as ?width) 
  WHERE
  {
    { select ?year (max(?pagestotal) as ?yeartotal)
  {              
    SELECT ?vol ?year (COUNT(?p) as ?pagestotal)
    {
     # hint:Query hint:optimizer "None".
      ?volitem wdt:P179 wd:Q665807 . 
      ?volitem wdt:P577 ?pub .
      ?volitem wdt:P478 ?vol .
      BIND(YEAR(?pub) as ?year)
      OPTIONAL { 
        ?p wdt:P1433 wd:Q665807 ; wdt:P478 ?vol2 ; wdt:P31 wd:Q19389637 .
        FILTER( xsd:integer(?vol2) <= xsd:integer(?vol) )
      }      
    }
    GROUP BY ?vol ?year
  }                
  GROUP BY ?year
  ORDER BY DESC(?year)
    }
  }