Advertising by national marketers reached $87.3 billion in 1994, a 9.1% gain, Robert J. Coen, McCann-Erickson Worldwide senior VP-director of forecasting, told Advertising Age. The elections and Olympics helped fuel double-digit increases in TV ad outlays for the largest annual rate of growth for this medium since 1984. Local marketers also increased their ad expenditures 8%, to $62.7 million. National advertising in most media this year should again match or outpace overall economic growth, but TV will be hard-pressed to post significant gains coming off the 1994 Olympics and elections. Local ad demand should continue its upward momentum as the improvement of retailing spreads to all regions of the country and as more local marketers regain their competitive confidence, Mr. Coen said.