This actually made me want to look it up and see if it's true, and IT IS. Hippos actually kill more people annually than sharks! They kill roughly 2,900 people a year. Apparently, male hippos are extremely territorial of their stomping ground, and female hippos will attack anyone who proves to be a threat to their babies. Plus they can run 20 mph, which is weird because I always imagined them to be really slow.
As for sharks? Six people at most. (Kind of makes you wonder what the movie 'Jaws' would've been like if it were a hippo attacking that boat.)