FileNet Corp., a Costa Mesa manufacturer of...

FileNet Corp., a Costa Mesa manufacturer of computerized document storage systems, said its earnings plunged 80% last year, despite an 11.5% increase in sales. Earnings dropped to $1.37 million from $6.86 million in 1987. Sales rose to $53.9 million from $48.3 million a year ago. For the fourth quarter, earnings fell 78% to $620,000, from $2.8 million in 1987. The company had a loss of $2.2 million for the third quarter. Sales rose 7% to $18.4 million in the latest quarter from $17.2 million a year earlier. FileNet’s stock closed Tuesday at $9 per share, down 50 cents, in over-the-counter trading.