You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Switzerland

Context:
On 9 February 2014, Swiss voters narrowly approved by 50.3% a ballot initiative launched by the national conservative Swiss People's Party (SVP/UDC) to restrict immigration, and thus reintroducing a quota system on the influx of foreigners. This initiative was mostly backed by rural (57.6% approvals), suburban (51.2% approvals), and isolated cities (51.3% approvals) of Switzerland as well as by a strong majority (69.2% approval) in the canton of Ticino, while metropolitan centres (58.5% rejection) and the French-speaking part (58.5% rejection) of Switzerland rather rejected it. Some news commentators claim that this proposal de facto contradicts the bilateral agreements on the free movement of persons from these respective countries.

Question:
In February of 2014, what did Swiss voters narrowly approve to restrict?

immigration