In Switzerland, the people have a say in almost everything. Swiss citizens can propose legislation and they can overturn legislation already approved by parliament. Any change to the Swiss constitution must first pass by the people and so must a range of other things, anything from building a local gym to whether or not to legalize the consumption of cannabis. Popular votes in Switzerland take place at three levels at the municipal, Cantinal, or national level. This is in line with the principle of subsidiarity under which the central authority only performs tasks which cannot be handled at a lower level. A typical vote at municipal level might be on public construction projects. In the city of Zurich, for example, voters agreed to the building of a new stadium. In Bern, they approved the construction of a glass canopy over the tram and bus station. Certain police issues are also dealt with at municipal level. In San Colin, voters approved new police regulations allowing the police to order anyone being disruptive to leave a public place. At Cantinal level, voters have been asked about issues such as not smoking in restaurants or on the opening hours of shops at petrol stations. Educational issues also fall under Cantinal jurisdiction and so voters are asked to decide on issues such as whether attending kindergarten should become obligatory or not and on renovating university premises. Issues relevant to the whole of Switzerland are put to nationwide vote. Examples include the Schengen-Dublin Agreement with the EU on Justice and asylum or legislation recognizing same-sex registered partnerships. People vote around four times a year at the national level, possibly even more at a Cantinal or municipal level. Voter turnout is usually around 40%, depending on the topic. To date, foreign nationals have no political rights at the federal level. In only two Cantons, Nuscia-Tel and Jura, Anonswiss allow to vote at the Cantinal and municipal level. In Vaux and Freeburg, they can vote at the municipal level. A popular vote can refer to either a referendum or a popular initiative. There are two types of referendum, mandatory and optional. A mandatory referendum is the most frequent instrument at the national level. This type of referendum must be held if the parliament wants to make a change to the federal constitution. To join a super national community such as the UN or the EU, or to introduce urgent federal legislation without the required constitutional basis. An optional referendum is one which can be requested by Swiss citizens to challenge a piece of legislation already approved by parliament. An optional referendum is held if opponents of the new law collect 50,000 signatures within 100 days of the legislation being announced. An optional referendum can also be requested by the Cantons, if at least eight Cantons do so. Swiss citizens also have the right to propose new legislation and can do so by launching a popular initiative. A nationwide vote on the issue is held if the popular initiative committee manages to collect 100,000 signatures within 18 months. While direct democracy is one of the most important features of the Swiss political system, the main players in political decision making remain the parliament and government. Out of the 169 popular initiatives launched between 1848 and 2009, only 16 were accepted. But despite their low rate of success, popular initiatives can prompt discussions and influence the shaping of policy.