Crime rates declining in hard times. Why?

I got a link sent to me of a report from FBI, USA, that shows that crime rates declined during 2008. I haven’t found an analysis of the report yet but it sure is an interesting development. One would think that it would be the other way around during hard times. What can have happened/changed that had this effect on crimes in the US? Or is it perhaps a global phenomena? What do you think?

Read the report here: http://www.fbi.gov/page2/sept09/crimestats_091409.html