Two percent of Switzerland is 200k people. Which is about how many people immigrate there every year
The immigration rates don't change that, because the immigrants cannot vote. The net immigration is also smaller, at around 85k per year, not 200k. [2]
[1] https://www.bfs.admin.ch/bfs/de/home/statistiken/politik/abs...
[2] https://www.sem.admin.ch/sem/de/home/publiservice/statistik/...