NEW YORK — Circulation at the nation’s daily newspapers is falling faster than anticipated this year as readers continue their migration to the Internet and papers narrow their distribution to cut costs. The development, which compounds the fiscal challenge of plummeting advertising revenue, was revealed Monday when the Audit Bureau of Circulations released sales totals reported by newspapers for April through September. Combined weekday circulation of all 507 papers that reported circulation totals this year and last averaged 38,165,848 in the six months ending in September, 4.6 percent below 40,022,356 a year earlier. The aggregate drop was only 2.6 percent in the September 2007 period, compared with September 2006. Sunday circulation fell faster than daily – 4.8 percent, to 43,631,646 at the 571 papers with comparable totals. A year ago, Sunday circulation fell 3.5 percent. Daily circulation at 16 of the 25 largest papers fell more than 5 percent in the latest period. Circulation has been dropping at newspapers for decades, a trend sped up by readers shifting to the Internet. Newspapers also have lost advertising in recent years because of the Internet, and that decline accelerated this summer as the weak economy prompted advertisers […]