Updated from 9:15 a.m. ESTIt's not exactly double-digit growth, but it's as close as you can get. Wendy's International ( WEN) Thursday released strong March same-store sales, with its U.S. flagship restaurant group posting a 9.9% gain. It's the second consecutive 9.9% sales gain for the company-owned restaurant unit of the Dublin, Ohio-based hamburger giant. Wendy's franchise operations posted a 7.8% gain, slightly less than a month ago. The March 2004 performance is a significant turnaround from the same period last year when sales in both groups fell. Same-store sales at its Tim Horton chain rose 13.9% in the U.S and 8.5% in Canada in the period ended March 28. The company said: "We continue to produce excellent results with a focus on superior restaurant operations, new product introductions and promotions." In particular, the company promoted a new spinach chicken salad during the month. Wendy's releases first-quarter earnings April 22. Analysts expect the company to earn 43 cents a share, according to Thomson One Analytics. Shares rose 29 cents, or 0.7%, to $40.98.