Sample stacked bar chart

read "ef2015.csv"
extend jahr = 2015
read "ef2019.csv"
extend jahr = 2019
union
read "ef2019.csv"
extend jahr = 2020
union
select kanton == "Zürich"
project partei, jahr, fiktive_waehlende
format fiktive_waehlende "%02d"
​​deserialize
​delegate "barchart -stacks 1,1,0"
print