Switzerland voted on Sunday on whether to back a proposal to cap the country’s population in a ​referendum likened to Britain’s Brexit vote, which could have far-reaching consequences for the economy and Bern’s relations with the European Union. Driven by concern about ‌immigration, pressure on public services and housing, the constitutional change pitched by the right-wing Swiss People’s Party, or SVP, would mandate that the population must not exceed 10 million by 2050. Official projections put it on track to do so by the early 2040s.