Has it been studied what percentage of a nations population should be foreigners?

Question

I know that most naturally evolved countries like Germany, Italy, Austria, Spain, and Norway all have non-European populations of 10 percent or less. And in Japan although the non-Japanese population is 1.2% the Ministry of Foreign Affairs of that country has stated that the foreign population should be 3 percent or below. How did they come up with the 3 percent figure? I did email them but they never responded. Do you think it the 3 percent figure was studied some way? Or did they just throw out a random number? If they did study it, what factors would be involved? How do you think the Ministry of Foreign Affairs decided that the 3 percent figure was enough? I am interested in this sort of thing, because I want to be a demographer.

**naturally evolved: formed overtime, not man made like the USA, Canada etc.

Answer 1

Having lived in Japan for eight years, I can firmly assert that their government wants to hold down any mass influx of foreigners. They believe there are only two kinds of people on the planet: Nihon-jin (Japanese) and Gai-jin (literally "outside persons"). A non-Japanese can only achieve Japanese citizenship by taking the maiden name of his wife as his own last name. That way, he can be entered into her familiy registry (koseki-to-hon).The European nations you cited have more than 10% foreign born. Their liberal asylum laws have left them with a lot more folks than they bargained for. It's one of the driving forces behind the appeal of anti-immigrant parties in most of those countries.
I find their attempts at enlightening us about ethnic diversity laughable, since they have created large ghettos filled with those same refugees, even onto the third generation. There are over 2 million Turks in Germany. Yet, there are heavy objections in Cologne over building a mosque for the Turks who are part of the Islamic "Umma".
Simply put, the U.S. and Canada are nations of immigrants. Europe is made up of various xenophobic political states wrestling with the dying of their ethnic homogenity. Demographers don't do well in potential powder kegs like that.

Answer 2

At the risk of sounding critical of the Japanese, they are very much nationalists....They rarely marry outside their race and culture....I was surprised at this when I visited Hawaii last summer....There were MANY Japanese, but I never once saw an interracial marriage....It is strictly prohibited...I think it was done by design and not just a random number....

Answer 3

There is no empirically magic number. However, the rules should reflect the interests and preferences of the citizens and government of the host country.