Not really true, it's around 23% and on about 1,900,000 immigrants, over 85% are Europeans, 300,000 are Italians, 295,000 are Germans and 110,000 are French, which are not really immigrants in the real sense being official languages in Switzerland (Italians were over 450,000 in the 80s, so there are less Italians than before in Switzerland).
On the other side Germans were very few in the 80s and are now the second largest group, due to tax benefits Swiss banks can guarantuee to very rich people (Switzerland is basically a tax heaven, that's the main drive for immigration, they are not really having an "immigration problem" like other countries in Europe are facing).
One popular example of such auto inflicted "immigration" is Ingvar Kamprad, IKEA founder, who lived in Switzerland for 40 years or Carlo De Benedetti, industrialist and media publisher, who's born Italian but naturalized Swiss citizen .
One other point to consider is that immigration in Switzerland is also due U.N. agencies being there.
The third and last point: Switzerland is surrounded by Alps, immigrant go there using planes, they are not the kind of immigrants that come to Europe on shitty boats in the Mediterranean sea.