The sixth anniversary of 9/11 came and went, with what has come to pass for normality on the city’s darkest date: a walk-through at ground zero for victims’ families, and Rudy Giuliani observing a rare moment of silence. Just like old times, a suspicious powder turned up in the mail room at the Standard & Poor’s offices. Census data found that blacks appear to be leaving the city — an exodus that may increase after 704 code violations were found at a single Harlem apartment building. The toxic oil spill under Greenpoint was discovered to be bigger than anyone had imagined. HIV infections were once again on the rise.