单选题
The medical world is gradually realizing that the quality of the environment in hospitals may play a significant role in the process of recovery from illness. As part of a nation-wide effort in Britain to bring art out the galleries and into public places, some of the country's most talented artists have called in to transform older hospitals and to soften the hard edges of modern buildings. Of the 2 500 National health Service hospitals in Britain, almost 100 now have significant collections of contemporary art in corridors, waiting areas and treatment rooms. These recent initiatives owe a great deal to one artist, Peter Senior, who set up his studio at a Manchester hospital in north-eastern England. The quality of the environment may reduce the need for expensive drugs when a patient is recovering form an illness. A study has shown that patients who had a view on to a garden needed half the number of strong pain killers compared with patients who had no view at all or only a brick wall to look at during the early 1970s. he felt the artist had lost his place in modern society, and that art should be enjoyed by a wider audience. A typical hospital waiting room might have as many as 5 000 visitors each week. What better place to hold regular exhibitions of art? Senior held the first exhibition of his own paintings in the out-patients' waiting area of the Manchester royal Infirmary in 1975. Believed to be Britain's first hospital-artist, Senior was so much in demand that he was soon joined by a team of six young art school graduates. The effect is striking. Instead of the familiar long, barren corridors and dull waiting rooms, the visitors experience a full view of fresh colours, playful images and restful courtyards.
单选题
Compared with the total number of Britain's National Health Service hospitals, the hospitals which have art collections is only ______.