Of all the Asian population in America, only the Japanese are shrinking

It's interesting to note that before, during and right after WWII, the Japanese were the second highest Asian population in the US. We are now shrinking.
I think the cause for this phenomenon is based on the fact that Japan's economy has grown after the war, and they had no need to move to find jobs.
Japan is now the fourth largest economy based on GDP, but for its size and population, I believe they are doing a decent job of remaining competiive.