Detailed Instructions: In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.
Q: Passage: The Dublin Grand Opera Society (DGOS) was founded in 1941 by Captain (later Colonel) William O'Kelly and a group of opera enthusiasts with John McCormack as its patron. The shows were cast with local singers and a volunteer chorus. Initially the music was provided by the orchestra of the Irish Army music school, and later by the Radio Eireann Symphony Orchestra. The Society put on two one-week seasons of opera throughout the years of World War II. After the war ended the DGOS presented performances by European opera companies such as the Opera-Comique, Hamburg Opera and the Netherlands Opera. From the mid 1950s to 1966, the Society, concentrated on Italian opera with the help of sponsorship from the Italian government. During that time numerous Italian stars and rising stars of the day appeared there, including Luciano Pavarotti who sang in Rigoletto, La traviata, and La boheme. The Italian sponsorship ended in 1966, but the Arts Council of Ireland and the Bord Failte (Ireland's tourist board) continued to provide guarantees for any financial losses. New opera companies were brought in, including the Romanian National Opera and the Prague National Theatre.
Link Information: none Answer: none
A:
Which European opera company presented by DGOS has been in operation for the greatest amount of years?