On just my first search, I found a statistic (http://tiny.cc/W6M35) that says that 86% of sex offenders (for this statistic, these were offenders researched in the UK) admitted using child porn as a precurser to worse offenses.

I don’t feel that owning/transmitting child porn is any less severe than actually touching a child. Some child somewhere was violated to get those pictures. By owning/transmitting and probably paying for those pictures, you’re engaging in a form of child trafficking.