(UPDATED COVERAGE, July 3) For a full year, restaurant operators have been optimistic about their business and the most recent survey by the National Restaurant Association shows they believe positive trends will continue for them through the rest of 2012.

The monthly Restaurant Performance Index and accompanying survey for May showed restaurant operators reporting increases in same-store sales for the 12th consecutive month, according to an NRA news release. The performance index was above the 100 mark in May for the seventh consecutive month. An index above 100 signifies expansion in key restaurant industry indicators.

Officials at Subway, which recently topped 37,000 locations worldwide and is considered the largest restaurant chain based on that number, there is agreement that restaurant business is in a stable growth pattern.

“Our growth coupled with the (NRA) report shows that the restaurant business is growing and that means the use of fresh produce is up, especially at Subway where fresh produce is so important to our menu,” said Les Winogard, spokesman for the Milford, Conn.-based chain.

Winogard said he thought the dining out public is increasingly opting for restaurants and menu selections that include more fresh produce because of nationwide campaigns by business and government to raise awareness about its health benefits.

In terms of sales, 61% percent of restaurant operators reported same-store sales gains between May 2011 and May 2012, up from the 57% that reported a sales gain in April. Many indicated they believe the trend will hold in the coming months: 48% expect to have higher sales in next six months, compared to the same period in 2011, while only 8% expect sales to drop.

Additional evidence that the U.S. restaurant industry is in full recovery mode comes from the Census Bureau in a monthly retail trade survey.

For May, the survey for “food services and drinking places” showed sales up 7.4% this year compared to May 2011. Sales had been flat for most of 2008-10, according to the survey. The Census numbers show sales in May this year 17% higher than the June 2009 level when government officials said the recession had ended.

Sales at “full service restaurants” were up by 8.7% year-over-year in April, according to the Census retail survey. Statistics on full-service restaurants for May are not yet available.