Tourism in Paris is a major income source. Paris received 12.6 million visitors in 2020, measured by hotel stays, a drop of 73 percent from 2019, due to the COVID-19 pandemic. The number of foreign visitors declined by 80.7 percent. Museums re-opened in 2021, with limitations on the number of visitors at a time and a requirement that visitors wear masks. In 2018, 17.95 million international, overnighting tourists visited the city, mainly for sightseeing and shopping (and estimated to be well over double if including domestic overnighting visitors). Top sights include Notre Dame (12 million visitors in 2017), Disneyland Paris , Sacre Cœur (10), the Versailles Palace (7.7), the Louvre Museum (6.9), the Eiffel Tower (5.9), Centre Pompidou (3.33), and the Musée d'Orsay (3 million). The largest numbers of foreign tourists who come to the Paris region are British, American, German, Italian, Chinese, Indian and Canadian.