| Year | |
|---|---|
| 1989 | 3,516.7 |
| 1990 | 3,516.7 |
| 1991 | 3,516.7 |
| 1992 | 3,516.7 |
| 1993 | 3,516.7 |
| 1994 | 3,516.7 |
| 1995 | 3,516.7 |
| 1996 | 3,489.7 |
| 1997 | 3,516.7 |
| 1998 | 3,516.7 |
| 1999 | 3,478.8 |
| 2000 | 3,643.8 |
| 2001 | 3,608.7 |
| 2002 | 3,608.7 |
| 2003 | 3,608.7 |
| 2004 | 3,595.3 |
| 2005 | 3,598.0 |
| 2006 | 3,598.0 |
| 2007 | 3,598.0 |
| 2008 | 3,598.0 |
| 2009 | 3,598.0 |
| 2010 | 3,597.0 |
| 2011 | 3,597.1 |
| 2012 | 3,595.1 |
| 2013 | 3,824.9 |
| 2014 | 3,716.1 |
| 2015 | 3,828.5 |
| 2016 | 3,833.5 |
| 2017 | 3,833.5 |