WASHINGTON (AP) — A survey of chief executives at the largest U.S. companies shows a growing number are optimistic about the economy's prospects for the next six months and expect to boost hiring.

The Business Roundtable says its index measuring CEO outlook rose to 84.5 in the October-December quarter. That's up from 79.1 in the July-September quarter.

The group is an association of chief executives at the 200 largest U.S. companies. Any reading above 50 suggests expansion.

The survey noted that 34 percent of the executives expect their companies will increase hiring in the next six months, up from 32 percent in the previous survey.

The CEOs expect the economy will grow 2.2 percent next year, unchanged from the previous two surveys.

Roughly two-thirds of those surveyed expect their company's sales to increase.