First of all, please for the love of your god, if you're referring to the Syrian's coming to the European countries over the past months; they're not "immigrants" they are refugees. There is a huge difference.
Secondly I doubt it has increased. It was the same case in my country Denmark, the media had a story every second week about a refugee doing some criminal act, and tried to blow it up as "the refugees are making our country less safe", but in reality, when the police published their report, the criminal activity was actually lower than what it used to be.
What I'm saying is, the media loves a good story about a criminal refugee, since it, sadly, matches many peoples picture of said refugees. But honestly, I'm more afraid of those, that are "afraid" of the refugees, than I am of the refugees.