Shark attacks are rare, but you wouldn’t know it watching the 20th anniversary of Shark Week on the Discovery Channel. From catching a few of the shows so far this week, it seems like swimmers and scuba divers serve as chum more often than not for great whites and company. (Sheesh. And we needed another reason to stay out of Santa Monica beaches?) On Sunday, the two-hour “Ocean of Fear: The Worst Shark Attack......