DETROIT—Mazda Motor Corp. expects the rollout of three new sport-utility vehicles, starting with the CX-50 next year, will help the Japanese automaker boost U.S. new-vehicle sales by a third by mid-decade, the company’s North American chief executive said on Monday. The company expects U.S. sales to finish this year “on the order of 330,000,” up from almost 280,000 last year, when supplies were hurt by the semiconductor shortage, Jeff Guyton said in an interview after Mazda unveiled the mid-sized CX-50. Mazda’s U.S. sales through October this year were up 30 percent to almost 293,000. With two larger SUVs joining the CX-50 by 2023, Guyton sees sales jumping further. “We do see a significant increase coming from CX-50, and the CX-70 and CX-90,” he said. “Maybe those don’t all mature in 2022, but by the middle of the decade, I would hope that we’re on par for 450,000 in the U.S.” …