| 年份 | 单位：% |
| 2011 | 15.49 |
| 2010 | 14.31 |
| 2009 | 14.01 |
| 2008 | 13.06 |
| 2007 | 12.78 |
| 2006 | 12.23 |
| 2005 | 11.00 |
| 2004 | 9.95 |
| 2003 | 8.61 |
| 2002 | 7.04 |
| 2001 | 5.47 |
| 2000 | 4.43 |
| 1999 | 4.07 |
| 1998 | 3.91 |
| 1997 | 3.41 |
| 1996 | 2.97 |
| 1995 | 2.97 |
| 1994 | 2.17 |
| 1993 | 1.31 |
| 1992 | 1.03 |
| 1991 | 0.46 |
| 1990 | 1.40 |
| 1989 | 1.12 |
| 1988 | 0.96 |
| 1987 | 0.83 |
| 1986 | 0.60 |
| 1985 | 0.58 |
前瞻产业研究院 咨询·服务