Question: How many times did plague occur in the birthplace of La Silvia's composer?

Knowledge 1: Orlando furioso (Vivaldi, 1714)
Orlando furioso RV 819 (, Teatro San Angelo, Venice 1714) is a three-act opera surviving in manuscript in Antonio Vivaldi's personal library, only partly related to his better known Orlando furioso (RV 728) of 1727. It is a recomposition of an "Orlando furioso" written by Giovanni Alberto Ristori which had been very successfully staged by Vivaldi and his father's "impresa" in 1713, and whose music survives in a few fragments retained in the score of RV 819. Therefore, Vivaldi's first cataloguer Peter Ryom did not assign the opera a RV number, but catalogued it as RV Anh. 84. The libretto was by Grazio Braccioli. [SEP] Knowledge 2: Black Death
In 1466, perhaps 40,000 people died of the plague in Paris. During the 16th and 17th centuries, the plague was present in Paris around 30 per cent of the time. The Black Death ravaged Europe for three years before it continued on into Russia, where the disease was present somewhere in the country 25 times between 1350 to 1490. Plague epidemics ravaged London in 1563, 1593, 1603, 1625, 1636, and 1665, reducing its population by 10 to 30% during those years. Over 10% of Amsterdam's population died in 1623–25, and again in 1635–36, 1655, and 1664. Plague occurred in Venice 22 times between 1361 and 1528. The plague of 1576–77 killed 50,000 in Venice, almost a third of the population. Late outbreaks in central Europe included the Italian Plague of 1629–1631, which is associated with troop movements during the Thirty Years' War, and the Great Plague of Vienna in 1679. Over 60% of Norway's population died in 1348–50. The last plague outbreak ravaged Oslo in 1654. [SEP] Knowledge 3: La Silvia
La Silvia (RV 734) is an "dramma pastorale per musica" in three acts by Antonio Vivaldi to an Italian libretto by Enrico Bissari. It was first performed on 28 August 1721 at the Teatro Regio Ducale in Milan on the occasion of the birthday celebrations of the Austrian Empress Elisabeth Christine, wife of Emperor Charles VI of Austria.
Knowledge 1: La Silvia
La Silvia (RV 734) is an "dramma pastorale per musica" in three acts by Antonio Vivaldi to an Italian libretto by Enrico Bissari. It was first performed on 28 August 1721 at the Teatro Regio Ducale in Milan on the occasion of the birthday celebrations of the Austrian Empress Elisabeth Christine, wife of Emperor Charles VI of Austria. [SEP] Knowledge 2: Orlando furioso (Vivaldi, 1714)
Orlando furioso RV 819 (, Teatro San Angelo, Venice 1714) is a three-act opera surviving in manuscript in Antonio Vivaldi's personal library, only partly related to his better known Orlando furioso (RV 728) of 1727. It is a recomposition of an "Orlando furioso" written by Giovanni Alberto Ristori which had been very successfully staged by Vivaldi and his father's "impresa" in 1713, and whose music survives in a few fragments retained in the score of RV 819. Therefore, Vivaldi's first cataloguer Peter Ryom did not assign the opera a RV number, but catalogued it as RV Anh. 84. The libretto was by Grazio Braccioli. [SEP] Knowledge 3: Black Death
In 1466, perhaps 40,000 people died of the plague in Paris. During the 16th and 17th centuries, the plague was present in Paris around 30 per cent of the time. The Black Death ravaged Europe for three years before it continued on into Russia, where the disease was present somewhere in the country 25 times between 1350 to 1490. Plague epidemics ravaged London in 1563, 1593, 1603, 1625, 1636, and 1665, reducing its population by 10 to 30% during those years. Over 10% of Amsterdam's population died in 1623–25, and again in 1635–36, 1655, and 1664. Plague occurred in Venice 22 times between 1361 and 1528. The plague of 1576–77 killed 50,000 in Venice, almost a third of the population. Late outbreaks in central Europe included the Italian Plague of 1629–1631, which is associated with troop movements during the Thirty Years' War, and the Great Plague of Vienna in 1679. Over 60% of Norway's population died in 1348–50. The last plague outbreak ravaged Oslo in 1654.
Knowledge 1: Orlando furioso (Vivaldi, 1714)
Orlando furioso RV 819 (, Teatro San Angelo, Venice 1714) is a three-act opera surviving in manuscript in Antonio Vivaldi's personal library, only partly related to his better known Orlando furioso (RV 728) of 1727. It is a recomposition of an "Orlando furioso" written by Giovanni Alberto Ristori which had been very successfully staged by Vivaldi and his father's "impresa" in 1713, and whose music survives in a few fragments retained in the score of RV 819. Therefore, Vivaldi's first cataloguer Peter Ryom did not assign the opera a RV number, but catalogued it as RV Anh. 84. The libretto was by Grazio Braccioli. [SEP] Knowledge 2: Black Death
In 1466, perhaps 40,000 people died of the plague in Paris. During the 16th and 17th centuries, the plague was present in Paris around 30 per cent of the time. The Black Death ravaged Europe for three years before it continued on into Russia, where the disease was present somewhere in the country 25 times between 1350 to 1490. Plague epidemics ravaged London in 1563, 1593, 1603, 1625, 1636, and 1665, reducing its population by 10 to 30% during those years. Over 10% of Amsterdam's population died in 1623–25, and again in 1635–36, 1655, and 1664. Plague occurred in Venice 22 times between 1361 and 1528. The plague of 1576–77 killed 50,000 in Venice, almost a third of the population. Late outbreaks in central Europe included the Italian Plague of 1629–1631, which is associated with troop movements during the Thirty Years' War, and the Great Plague of Vienna in 1679. Over 60% of Norway's population died in 1348–50. The last plague outbreak ravaged Oslo in 1654. [SEP] Knowledge 3: Black Death
Medical knowledge had stagnated during the Middle Ages. The most authoritative account at the time came from the medical faculty in Paris in a report to the king of France that blamed the heavens, in the form of a conjunction of three planets in 1345 that caused a "great pestilence in the air". This report became the first and most widely circulated of a series of plague tracts that sought to give advice to sufferers. That the plague was caused by bad air became the most widely accepted theory. Today, this is known as the Miasma theory. The word 'plague' had no special significance at this time, and only the recurrence of outbreaks during the Middle Ages gave it the name that has become the medical term.

Answer: 22