I'm not sure. Plenty of people swim in waters where sharks are regularly observed. And still the attacks are low. And further, with many attacks, I think in particular great-whites, they back off after the first bite, which allows for much greater survivability. So the ratio of "shark contact" to "sharks win" is probably low. And if you also add in fishing for sharks (such as for fins) humans probably kill a lot more sharks than the other way around.
Certainly the amount of contact plays a roll. That's why dogs are so much higher than wolves for instance. But it's also true that most of the time people spend swimming around sharks, they don't get bitten. How the ratio of attacks to contacts compares between sharks and dogs or other animals I don't know; agreed that would be somewhat interesting!
