Well, UPN was targeted more at a more modern, urban audience. It wasn't exactly the best network for a science fiction show.
When Enterprise was on, I couldn't even watch it, because we didn't have local channels, just satellite. So I never even watched most Enterprise until a couple of years after it was over when pirated copies started to appear online.
However we were selected to participate in the Nielsen ratings the year it was to be canceled. Even though I literally couldn't watch the show, we made sure to give Enterprise the best rating.