| 年份 | 产量 | 年份 | 产量 |
| 1986 | ＞0.7 | 1995 | 6.327 |
| 1987 | 1.895 | 1996 | 6.170 |
| 1988 | 2.360 | 1997 | 8.020 |
| 1989 | 2.400 | 1998 | 9.270 |
| 1990 | 1.641 | 1999 | 10.650 |
| 1991 | 1.385 | 2000 | 12.300 |
| 1992 | 3.501 | 2001 | 15.170 |
| 1993 | 4.510 | 2002 | 21.200 |
| 1994 | 6.150 | 2003 | |