systems; however, for the most part, subway stations lack air-cooling systems due to their expense, and only a few stations have ceiling fans. Artwork Many stations are decorated with intricate ceramic tile work, some of it dating back to 1904 when the subway first opened. The subway tile artwork tradition continues in a Percent for Art program. The MTA Arts & Design program oversees art in the subway system. Permanent installations, such as sculpture, mosaics, and murals; photographs displayed in lightboxes encourage people to use mass transit. In addition, commissioned art displayed in stations and "art cards", some displaying poetry, are in many of the trains themselves in unused advertisement fixture slots. Some of the art is by internationally known artists such as Elizabeth Murray's Blooming, displayed at Lexington Avenue/59th Street station. Accessibility Since the majority of the system was built before 1990, the year the Americans with Disabilities Act (ADA) went into effect, many New York City Subway stations were not designed to be handicapped-accessible. Since then, elevators have been built in newly constructed stations to comply with the ADA. (Most grade-level stations required little modification to meet ADA standards.) In addition, the MTA identified "key stations", high-traffic and/or geographically important stations, which must conform to the ADA when they are extensively renovated. , out of total stations in the system, 119 are accessible; many of them have AutoGate access. Five stations on the Staten Island Railway are also accessible. Additionally, there are 16 more non-ADA-accessible stations with cross-platform interchanges, as well as other same-platform transfers, available, though the MTA notes that the gaps between train cars and platforms at these stations may nonetheless exceed the maximums established by the ADA. Entertainment While a permit is not required for performances in the subway, certain codes of conduct are required. Any musician/entertainer may perform in subway mezzanines and platforms. On platforms, there may be no amplifications as this is part of MTA policies: Performers must not be within of a token booth or from an MTA office/tower, blocking access to an escalator, stairwell, or elevator, interfering with transit services or passenger movement; or in an area where construction is occurring. In addition, performance is prohibited during public service announcements and may be no louder than 85 dBA at away or 70 dBa at from a token booth. Performances are prohibited in subway cars. Since 1987, MTA has sponsored the "Music