Of the nation’s 20 largest newspapers, the San Francisco Chronicle had the largest decrease in circulation, according to Audit Bureau of Circulations figures released Monday. The Chron’s circulation dropped 15.6 percent from the same period a year earlier. Publisher Frank Vega (pictured) said the declines were due to a deliberate strategy of reducing the amount of papers provided at no charge to advertisers. The cutbacks involved papers that “advertisers didn’t value, were quite costly and essentially had no impact on our readership,” said Chron spokeswoman Patricia Hoyt. But industry experts quoted by the LA Times said such arguments aren’t very convincing coming from newspapers [such as the Chron] which had said the same thing last year. “You can only cry wolf so many times,” said Vice President Colby Atwood of Borell Associates Inc., which advises newspapers on Internet strategy. “Part of the decline is genuine decline.” The Mercury News, which saw its circulation fall 7.7 percent to 242,865, blamed the loss on a decision to increase its sales price from a quarter to 50 cents. [AP: Newspaper circulation down, Web readers up]