The successful initiatives date to the following years: 1893, 1908 (absinthe), 1918, 1920 (gambling), 1921, 1928 (gambling), 1949, 1982, 1987 (protection of wetlands), 1990 (nuclear power moratorium), 1993 (National Day), 1994 (protection of alpine ecosystems), 2002 (UN membership), 2004, 2005, 2008, 2009 (minaret ban), 2010, 2012, 2013 (executive pay), 2014 (immigration), 2014 (convicted child sex offender work ban).
[1] The most frequent themes tackled by initiatives are healthcare, taxes, welfare, drug policy, public transport, immigration, asylum, and education.
There are only two kinds of restrictions on the content: It is different from the mandatory referendum in that in a popular initiative, the proposition to change the constitution comes from the population and not from the parliament.
The authorities, even if they don't like it, cannot prevent an initiative which has collected enough signatures from being held, but they can make a counter proposal, known as counter-project.
[5] Some critics argue that it undermines the whole Swiss political system, based on compromise and adaptation to one another, as it suppresses any possibility to negotiate on an issue (an initiative can only be accepted or rejected as a whole).