Why is Hosni Mubarak considered a dictator?

In school we were asked to do a project on world Dictators, mine being Hosni Mubarak, president of Egypt. Hes even ranked 17 in parade.com on the list of the worlds current worst dictators. As I have been researching though, I have come across no real displays of dictatorship. Everything said seems to state the opposite. The only thing I could find was a tightening of the law on who gets to run for presidential candidacy. So why is he considered a dictator. Any help on this would be great.