| Year | Import | Export | |
| Metric Tons | |||
| 1989 | 1179 | 1672 | |
| 1990 | 1361 | 1581 | |
| 1991 | 1684 | 702 | |
| 1992 | 2333 | 828 | |
| 1993 | 1868 | 47 | |
| 1994 | 1970 | 35 | |
| 1995 | 2417 | 33 | |
| 1996 | 2417 | 13 | |
| 1997 | 3228 | 247 | |
| 1998 | 4445 | 116 | |
| 1999 | 3363 | 108 | |
| 2000 | 5642 | 104 | |
| 2001 | 5732 | 84 | |
| 2002 | 6982 | 62 | |
| 2003 | 8462 | 55 | |
| 2004 | 9551 | 84 | |
| 2005 | 9653 | 883 | |
| 2006 | 11079 | 469 | |
| 2007 | 10166 | 200 | |
| 2008 | 10764 | 355 | |