Question: How much of the glaciation in the country of citizenship of the performer of Alice Polka disappeared?

full_context: Document 1: Alps: Glaciers end in ice caves (the Rhone Glacier), by trailing into a lake or river, or by shedding snowmelt on a meadow. Sometimes a piece of glacier will detach or break resulting in flooding, property damage and loss of life. In the 17th century about 2500 people were killed by an avalanche in a village on the French-Italian border; in the 19th century 120 homes in a village near Zermatt were destroyed by an avalanche.
Document 2: Warsaw: Thanks to numerous musical venues, including the Teatr Wielki, the Polish National Opera, the Chamber Opera, the National Philharmonic Hall and the National Theatre, as well as the Roma and Buffo music theatres and the Congress Hall in the Palace of Culture and Science, Warsaw hosts many events and festivals. Among the events worth particular attention are: the International Frédéric Chopin Piano Competition, the International Contemporary Music Festival Warsaw Autumn, the Jazz Jamboree, Warsaw Summer Jazz Days, the International Stanisław Moniuszko Vocal Competition, the Mozart Festival, and the Festival of Old Music.
Document 3: Buckingham Palace: Court presentations of aristocratic young ladies to the monarch took place at the palace from the reign of Edward VII. These young women were known as débutantes, and the occasion—termed their "coming out"—represented their first entrée into society. Débutantes wore full court dress, with three tall ostrich feathers in their hair. They entered, curtsied, and performed a choreographed backwards walk and a further curtsy, while manoeuvring a dress train of prescribed length. (The ceremony, known as an evening court, corresponded to the "court drawing rooms" of Victoria's reign.) After World War II, the ceremony was replaced by less formal afternoon receptions, usually without choreographed curtsies and court dress.
Document 4: Classical period (music): However, Vienna's fall as the most important musical center for orchestral composition during the late 1820s, precipitated by the deaths of Beethoven and Schubert, marked the Classical style's final eclipse -- and the end of its continuous organic development of one composer learning in close proximity to others. Franz Liszt and Frédéric Chopin visited Vienna when they were young, but they then moved on to other cities. Composers such as Carl Czerny, while deeply influenced by Beethoven, also searched for new ideas and new forms to contain the larger world of musical expression and performance in which they lived.
Document 5: Frédéric Chopin: In London Chopin took lodgings at Dover Street, where the firm of Broadwood provided him with a grand piano. At his first engagement, on 15 May at Stafford House, the audience included Queen Victoria and Prince Albert. The Prince, who was himself a talented musician, moved close to the keyboard to view Chopin's technique. Broadwood also arranged concerts for him; among those attending were Thackeray and the singer Jenny Lind. Chopin was also sought after for piano lessons, for which he charged the high fee of one guinea (£1.05 in present British currency) per hour, and for private recitals for which the fee was 20 guineas. At a concert on 7 July he shared the platform with Viardot, who sang arrangements of some of his mazurkas to Spanish texts.
Document 6: Alps: The Alps provide lowland Europe with drinking water, irrigation, and hydroelectric power. Although the area is only about 11 percent of the surface area of Europe, the Alps provide up to 90 percent of water to lowland Europe, particularly to arid areas and during the summer months. Cities such as Milan depend on 80 percent of water from Alpine runoff. Water from the rivers is used in over 500 hydroelectricity power plants, generating as much as 2900 kilowatts of electricity.
Document 7: Switzerland: Switzerland lies between latitudes 45° and 48° N, and longitudes 5° and 11° E. It contains three basic topographical areas: the Swiss Alps to the south, the Swiss Plateau or Central Plateau, and the Jura mountains on the west. The Alps are a high mountain range running across the central-south of the country, comprising about 60% of the country's total area. The majority of the Swiss population live in the Swiss Plateau. Among the high valleys of the Swiss Alps many glaciers are found, totalling an area of 1,063 square kilometres (410 sq mi). From these originate the headwaters of several major rivers, such as the Rhine, Inn, Ticino and Rhône, which flow in the four cardinal directions into the whole of Europe. The hydrographic network includes several of the largest bodies of freshwater in Central and Western Europe, among which are included Lake Geneva (also called le Lac Léman in French), Lake Constance (known as Bodensee in German) and Lake Maggiore. Switzerland has more than 1500 lakes, and contains 6% of Europe's stock of fresh water. Lakes and glaciers cover about 6% of the national territory. The largest lake is Lake Geneva, in western Switzerland shared with France. The Rhône is both the main source and outflow of Lake Geneva. Lake Constance is the second largest Swiss lake and, like the Lake Geneva, an intermediate step by the Rhine at the border to Austria and Germany. While the Rhône flows into the Mediterranean Sea at the French Camarque region and the Rhine flows into the North Sea at Rotterdam in the Netherlands, about 1000 km apart, both springs are only about 22 km apart from each other in the Swiss Alps.
Document 8: Buckingham Palace: Widowed in 1861, the grief-stricken Queen withdrew from public life and left Buckingham Palace to live at Windsor Castle, Balmoral Castle and Osborne House. For many years the palace was seldom used, even neglected. In 1864, a note was found pinned to the fence of Buckingham Palace, saying: "These commanding premises to be let or sold, in consequence of the late occupant's declining business." Eventually, public opinion forced the Queen to return to London, though even then she preferred to live elsewhere whenever possible. Court functions were still held at Windsor Castle, presided over by the sombre Queen habitually dressed in mourning black, while Buckingham Palace remained shuttered for most of the year.
Document 9: Alps: The Alps are a classic example of what happens when a temperate area at lower altitude gives way to higher-elevation terrain. Elevations around the world that have cold climates similar to those of the polar regions have been called Alpine. A rise from sea level into the upper regions of the atmosphere causes the temperature to decrease (see adiabatic lapse rate). The effect of mountain chains on prevailing winds is to carry warm air belonging to the lower region into an upper zone, where it expands in volume at the cost of a proportionate loss of temperature, often accompanied by precipitation in the form of snow or rain. The height of the Alps is sufficient to divide the weather patterns in Europe into a wet north and a dry south because moisture is sucked from the air as it flows over the high peaks.
Document 10: Hotel Sacher: The Hotel Sacher is a five-star hotel located in the Innere Stadt first district of Vienna, Austria, vis-à-vis to the Vienna State Opera. It is famous for the specialty of the house, the Sachertorte, a chocolate cake with apricot filling. There is also an art gallery in the hotel with works from the 19th century. The hotel is built near the former residence of Antonio Vivaldi.
Document 11: Buckingham Palace: Before Prince Albert's death, the palace was frequently the scene of musical entertainments, and the greatest contemporary musicians entertained at Buckingham Palace. The composer Felix Mendelssohn is known to have played there on three occasions. Johann Strauss II and his orchestra played there when in England. Strauss's "Alice Polka" was first performed at the palace in 1849 in honour of the queen's daughter, Princess Alice. Under Victoria, Buckingham Palace was frequently the scene of lavish costume balls, in addition to the usual royal ceremonies, investitures and presentations.
Document 12: Vienna Walzer Orchestra: The Vienna Walzer Orchestra (German: Wiener Walzer Orchester) is a chamber orchestra based in Vienna, Austria that specializes in traditional Viennese waltzes, polkas, marches and operetta arias from composers such as: J. Strauss II, F. Lehár, C.M. Ziehrer, among others. Their concerts also always include performances by ballet dancers and opera singers.
Document 13: Frédéric Chopin: In 1817 the Saxon Palace was requisitioned by Warsaw's Russian governor for military use, and the Warsaw Lyceum was reestablished in the Kazimierz Palace (today the rectorate of Warsaw University). Fryderyk and his family moved to a building, which still survives, adjacent to the Kazimierz Palace. During this period, Fryderyk was sometimes invited to the Belweder Palace as playmate to the son of the ruler of Russian Poland, Grand Duke Constantine; he played the piano for the Duke and composed a march for him. Julian Ursyn Niemcewicz, in his dramatic eclogue, "Nasze Przebiegi" ("Our Discourses", 1818), attested to "little Chopin's" popularity.
Document 14: Waltzes from Vienna: Waltzes from Vienna is a 1934 British musical film directed by Alfred Hitchcock, also known as Strauss' Great Waltz. It was part of the cycle of operetta films made in Britain during the 1930s.
Document 15: Alps: High levels of precipitation cause the glaciers to descend to permafrost levels in some areas whereas in other, more arid regions, glaciers remain above about the 3,500 m (11,483 ft) level. The 1,817 square kilometres (702 sq mi) of the Alps covered by glaciers in 1876 had shrunk to 1,342 km2 (518 sq mi) by 1973, resulting in decreased river run-off levels. Forty percent of the glaciation in Austria has disappeared since 1850, and 30% of that in Switzerland.
ground_truth: Forty percent
sub_queries: Who performed Alice Polka in honor of Princess Alice? Answer: Johann Strauss II
Johann Strauss II >> country of citizenship Answer: Austria
How much of the glaciation in Austria disappeared? Answer: Forty percent