NEW YORK The newspaper industry has experienced the worst drop in advertising revenue in more than 50 years. According to new data released by the Newspaper Association of America, total print advertising revenue in 2007 plunged 9.4% to $42 billion compared to 2006 -- the most severe percent decline since the association started measuring advertising expenditures in 1950. The drop-off points to an economic slowdown on top of the secular challenges faced by the industry. The second worst decline in advertising revenue occurred in 2001 when it fell 9.0%. Total advertising revenue in 2007 -- including online revenue -- decreased...