is operated under the Cost-share Program, the Secretary shall annually calculate a benefit-to-cost ratio with respect to the tower. (B) Towers participating in contract tower program In the case of an air traffic control tower that is operated under the Contract Tower Program, the Secretary shall not calculate a benefit-to-cost ratio after the date of enactment of this subsection with respect to the tower unless the Secretary determines that the annual aircraft traffic at the airport where the tower is located has decreased— (i) by more than 25 percent from the previous year