a frenzied mergers-and-acquisitions market and dot-com mania combined to fuel the largest year-to-year growth rate for advertising agencies in the past two decades. U.S. agencies' gross income soared 22.2% to $18.3 billion, according to Advertising Age's 56th annual Agency Report. Hard-charging interactive steamed to $1.27 billion of the aggregate, a 53.7% advance that if absent from the total would have left agencies up just 16.7%. More than 300 acquisitions also fattened U.S. agencies in 1999, continuing an M&A trend that has broadened integrated services and boosted the overall billings base. Omnicom Group retained its crown as the world's largest ad organization at $5.74 billion in gross income. The report begins after Page 70.