I don't think that higher rate of reporting alone is responsible for the abnormal stats. Recently, Nigel Farage called Sweden as the rape capital of the world. The 2012 UN international rape rate comparison showed Sweden to have the highest rate of rape in Europe and the second highest in the world (I am not talking about sexual molestation. I am talking about rape, where actual penetration occurred).
1960s and 1970s: 1.2 - 2.6 times more than the Swedes.
1980s: 2.1 - 4.7 times more than the Swedes.
1990: 2.1 - 8.1 times more than the Swedes.
2000s: 2.1 - 19.5 times more than the Swedes.
I read somewhere that more than 50% of the rapes in Sweden are being committed by Somalis and Afghans, despite these two groups together constituting for less than 1% of the total population. The government response was laughable. They stopped publishing the ethnic origin of the perpetrators.