WASHINGTON (AP) – Justin Bieber’s “Baby” isn’t just an infectious pop song – it’s a history maker. The Recording Industry Association of America now says it’s the biggest single ever. The industry group has certified Bieber’s single as reaching Diamond status – in “Baby’s” case – platinum 12 times over, and counting. The Beeb tweets in response that he is “honored” by the designation. Back in May, the RIAA changed its formula for tallying record “sales” to include on-demand audio and Internet streams like Spotify and Vevo into the mix. That has helped boost the numbers for Bieber as well as for other artists who have a major online presence.