| 年度 | 实际值 |
|---|---|
| 1978 | 7.1 |
| 1979 | |
| 1980 | 7.6 |
| 1981 | |
| 1982 | |
| 1983 | |
| 1984 | |
| 1985 | 8.1 |
| 1986 | |
| 1987 | |
| 1988 | |
| 1989 | |
| 1990 | 8.9 |
| 1991 | |
| 1992 | |
| 1993 | |
| 1994 | |
| 1995 | 9.1 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 9 |
| 2000 | 9.1 |
| 2001 | 9.2 |
| 2002 | 9.2 |
| 2003 | 9.4 |
| 2004 | 9.4 |
| 2005 | 11.8 |
| 2006 | 11.9 |
| 2007 | 11.9 |
| 2008 | 12 |
| 2009 | 12.1 |
| 2010 | 12.2 |
| 2011 | 12.29 |
| 2012 | 12.4 |
| 2013 | 12.48 |
| 2014 | 12.56 |