Children of refugee's welcomed by Sweden - riot & hate Sweden - why?

NY Times    In Stockholm and other towns and cities last week, bands made up mostly of young immigrants set buildings and cars ablaze in a spasm of destructive rage rarely seen in a country proud of its normally tranquil, law-abiding ways. 

The disturbances, with echoes of urban eruptions in France in 2005 and Britain in 2011, have pushed Sweden to the center of a heated debate across Europe about immigration and the tensions it causes in a time of deep economic malaise. 

The riots, now subsiding, have produced less damage than the earlier ones in Paris and London, which also involved mostly immigrants. But the unrest has shaken Sweden, which has a reputation for welcoming immigrants and asylum seekers, including those fleeing violence in countries like Iraq, Somalia and Syria, and regularly ranks in surveys as one of the world’s happiest places. 

“I don’t know why anybody would want to burn our school,” Ms. Bromster said. “I can’t understand it. Maybe they are not so happy with life.”