Nikon 60mm AF-S G Micro

I just got a great deal on one of these. Mint shape with 3 1/5 years still left on the warranty. One thing I realized when I got home (didn't check cause I assumed they were all made in Japan) is that it was made in Taiwan. Now I really don't care as long as it is sharp, and that it is, and as long as it's well built, which seems to be not bad. My question is, did Nikon start off making them in Japan and then moved over to Taiwan or are the lenses made at both places at the same time??