Created in 2003 as part of the Medicare Modernization Act, Part D of Medicare was designed to provide financial aid for prescription medication purchases of Medicare beneficiaries. As of 2018, 43 million people receive prescription drug coverage under Part D; 58% of those are on a stand-alone prescription drug plan, as opposed to the Medicare Advantage plans that provide supplementary coverage. Though is is open to all Americans who receive Part A and/or Part B benefits, Part D is an entirely optional program.