In the second half of the 20th century, composers largely turned to other genres and composition techniques than those of the concerto. Composers who continued to contribute to the genre include Hans Werner Henze and György Ligeti. Composers performing the solo part of a concerto they composed for a live audience, which had been very common for over two and a half centuries, became even more exceptional. One of such exceptions was Deep Purple's "Concerto for Group and Orchestra". On the other hand, many concertos composed before the middle of the 20th century easily kept repertoire for concert performances and recordings. For instance, international competitions for instrumentalists such as the Van Cliburn Piano Competition and the Queen Elisabeth Competition require performances of concertos by the competitors.