Stocks drop, Dow's loss for year first since '02Fri Dec 30, 2005 6:50 PM ET By Vivianne RodriguesNEW YORK (Reuters) - U.S. stocks fell in the year's final trading session on Friday, pushing the Dow Jones industrial average to its first loss since 2002, while both the broad S&P 500 and the Nasdaq Composite Index booked gains for the third straight year.The Dow declined 0.61 percent in 2005, breaking its streak of back-to-back gains for 2003 and 2004.Meanwhile, the S&P 500 rose for a third consecutive year, advancing 3 percent -- just one-third of its 9 percent gain last year...