| 1980 | 1985 | 1990 | 1995 | 2000 | 2005 | 2010 | 2015 | |
| Chinese Mainland | 10.37% | 11.26% | 11.92% | 11.92% | 14.49% | 16.52% | 18.77% | 21.23% |
| Japan | 23.64% | 26.31% | 30.89% | 37.01% | 42.95% | 47.17% | 53.27% | 61.08% |
| Rep. of Korea | 11.20% | 13.67% | 18.01% | 23.39% | 29.29% | 37.12% | 43.18% | 49.10% |
| Chinese Taipei | 8.84% | 10.37% | 13.20% | 15.04% | 18.60% | 21.14% | 24.40% | 27.89% |
| USA | 21.90% | 23.73% | 25.60% | 26.65% | 26.99% | 27.84% | 30.52% | 34.44% |