Why do Japanese-pressed CDs sound better?

I have been trying to answer this question to myself for years now, but I can't seem to come up with a real answer. I have many CDs pressed in Japan and every one of them seems to sound better than the same CD pressed in any other country. So the question is what does Japan do differently than the other countries when they master/press a CD? Even DDD recordings seem to have more depth on Japan pressings. I can't say the difference is earth-shaking, but still it's noticeable to me. Anyone have any ideas? Is it just less jitter on the disc or is it something else?