Question: The composer of the opera "The Zoo" has composed how many major orchestral works?
Context: The following is a list of musical works by the English composer Arthur Sullivan, best known for his operatic collaborations with W. S. Gilbert.  In all, Sullivan's artistic output included 23 operas, 13 major orchestral works, eight choral works and oratorios, two ballets, one song cycle, incidental music to several plays, numerous hymns and other church pieces, and a large body of songs, parlour ballads, part songs, carols, and piano and chamber pieces. Orchestral Works by Tomas Svoboda (sometimes abridged as Orchestral Works) is a classical music album by the Oregon Symphony under the artistic direction of James DePreist, released by the record label Albany in 2003.  The album was recorded at the Arlene Schnitzer Concert Hall in Portland, Oregon during three performances in January and June 2000.  It contains three works by Tomáš Svoboda, a Czech-American composer who taught at Portland State University for more than 25 years: "Overture of the Season", Op. 89; "Concerto for Marimba and Orchestra", Op. 148; and Symphony No. 1 (of Nature), Op. 20.  The album's executive producers were Peter Kermani, Susan Bush, and Mark B. Rulison; Blanton Alspaugh served as the recording producer. Aaron Copland ( ; November 14, 1900December 2, 1990) was an American composer, composition teacher, writer, and later a conductor of his own and other American music.  Copland was referred to by his peers and critics as "the Dean of American Composers."  The open, slowly changing harmonies in much of his music are typical of what many people consider to be the sound of American music, evoking the vast American landscape and pioneer spirit.  He is best known for the works he wrote in the 1930s and 1940s in a deliberately accessible style often referred to as "populist" and which the composer labeled his "vernacular" style.  Works in this vein include the ballets "Appalachian Spring", "Billy the Kid" and "Rodeo", his "Fanfare for the Common Man" and Third Symphony.  In addition to his ballets and orchestral works, he produced music in many other genres including chamber music, vocal works, opera and film scores. Igor Štuhec (born 15 December 1932) is a contemporary Slovenian composer, who lives in Ljubljana and Maribor.  He studied composition at the Ljubljana Academy of Music under Lucijan Marija Škerjanc and Matija Bravničar.  He continued his studies at the Vienna Academy of Music and Dramatic Art under Hanns Jelinek, and also at the Darmstädter Ferienkurse.  After some early neo-classical orchestral works that show his mastery of traditional techniques, Štuhec gradually moved towards the adoption of new techniques in the early 1960s.  Although in 1955 he had produced a musique concrète composition in "Biological Transformation", the radical change came with the chamber pieces "Situacija" (1963) and "Silhuete" (1964) and the orchestral "Differentiations" (1964), all of which exhibit his assimilation of 12-note and aleatory procedures.  Štuhec's skill is particularly evident in miniatures such as the "Minikoncert", where his writing is at its most delicate and the textures are almost always crystal clear.  A later group of orchestral works extending his textural techniques, notably the concertos and the three "Entuziazmi" pieces, display a vivid imagination and a strong rhythmic momentum.  Also among his works are two operas, "Zupanova Micka" (1948) and Robert Boury (born December 28, 1946) is an American composer and pianist.  Boury was part of the revival of Ragtime led by William Albright and William Bolcom in the late sixties.  Boury has composed many types of instrumental works and in a variety of medias and genres, such as solo/duet piano works, art songs, both comic opera/opera seria, choral works, ragtime works, orchestral works and elect acoustic pieces. Frederic Austin did not assign opus numbers to any of his music.  His published output (apart from "The Beggar's Opera", "Polly" and "Perviligium Veneris") consists mainly of song settings for solo voice or chorus, while most of his major orchestral and other works remain in manuscript (see the 'MS' column).  Most of Austin's works can be accurately dated, though some (mostly lacking an extant MS) are undated: see the 'Year' column. Maria Newman (born Maria Louise Newman on January 18, 1962, in Los Angeles, California) is an award-winning American composer of classical music, and a critically acclaimed violinist, violist and pianist.  She is the youngest child of Alfred Newman, a major Hollywood film composer.  Maria holds the Louis and Annette Kaufman Composition Chair; and the Joachim Chassman Violin Chair at the Montgomery Arts House for Music and Architecture in Malibu, California, and is a founder of the Malibu Friends of Music.  Her library of original works represents a range of genres, from large-scale orchestral works, works for the ballet, chamber works, choral and vocal works, to new collaborative scores for vintage silent film.  She has been presented with many awards and commissions, including musical commendations from the United States Congress (2009), the California State Senate (2009), the California State Assembly (2009), the City of Malibu (2010), and the Annenberg Foundation (2011). Sir Arthur Seymour Sullivan MVO (13 May 1842 – 22 November 1900) was an English composer.  He is best known for his series of 14 operatic collaborations with the dramatist W. S. Gilbert, including "H.M.S. Pinafore", "The Pirates of Penzance" and "The Mikado".  His works include 23 operas, 13 major orchestral works, eight choral works and oratorios, two ballets, incidental music to several plays, and numerous hymns and other church pieces, songs, and piano and chamber pieces.  The best known of his hymns and songs include "Onward Christian Soldiers" and "The Lost Chord". The Zoo is a one-act comic opera, with music by Arthur Sullivan and a libretto by B. C. Stephenson, writing under the pen name of Bolton Rowe.  It premiered on 5 June 1875 at the St. James's Theatre in London (as an afterpiece to W. S. Gilbert's "Tom Cobb"), concluding its run five weeks later, on 9 July 1875, at the Haymarket Theatre.  There were brief revivals in late 1875, and again in 1879, before the opera was shelved. Sequoia is an orchestral composition by the American composer Joan Tower.  The work was commissioned by the American Composers Orchestra with support from the Jerome Foundation.  It was first performed on May 18, 1981 in Alice Tully Hall by the American Composers Orchestra under the conductor Dennis Russell Davies.  The piece is dedicated to the concertmistress and first horn player of the orchestra, Jean and Paul Ingraham, respectively.  "Sequoia" was Tower's first major orchestral composition and remains one of the composer's most performed works.
Answer: 13