Millions of Americans fork over, on average, more than $230 a year to rent set-top boxes from cable and other pay-television providers, and the government’s top TV regulator revealed its final proposal Thursday to loosen the cable industry’s tight grip on those devices.Federal Communications Commission Chairman Tom Wheeler announced that the proposal would require major cable and satellite operators to develop free apps that customers can use to access the companies’ content through alternative devices such as Apple TV or Amazon’s Fire TV.“We were motivated by the desire to give consumers relief, but we were also mandated to take action by Congress and the law, which says that consumers should be able to choose their preferred device to access pay-TV programming,” Wheeler wrote in a Los Angeles Times Op-Ed published Thursday.Under the terms of the plan, pay-television providers such as Comcast and Verizon would also have to provide a way for consumers to search for the content that they want, all in one place.