User blog comment:Pokegod85321/MAP QUIZ 13/@comment-32788589-20160909171924

Immigrants. This is the reason why it is not rural population, internet user percentage or fertile land percentage:

The countries are colored in a different color:

Green: Poland, Romania, Bulgaria, Bosnia and Herzegovina

Cyan-Green: Finland, Turkey, Albania, Czech Republic, Hungary, Lithuania, Serbia, Macedonia

Purple: Austria, Estonia, Sweden, Ireland, Spain

Pink-Purple: Croatia, Cyprus

Cyan: Italy, Greece, Portugal, Russia

Blue: Montenegro

Blue-Purple: Norway, Belarus, Ukraine, Moldova, Germany, the Netherlands, France

Dark Blue: Slovenia, Denmark, Belgium, Iceland

Dark Purple: Latvia

Red: Switzerland, Luxembourg, Andorra

Kosovo, Africa and the Middle East didn't show the percentage of immigrants.

I don't know Malta's percentage of immigrants