| Year | |
|---|---|
| 1989 | 309.8 |
| 1990 | 309.8 |
| 1991 | 554.7 |
| 1992 | 799.7 |
| 1993 | 1,044.5 |
| 1994 | 1,000.1 |
| 1995 | 948.8 |
| 1996 | 996.3 |
| 1997 | 996.3 |
| 1998 | 963.3 |
| 1999 | 963.3 |
| 2000 | 947.5 |
| 2001 | 947.5 |
| 2002 | 841.5 |
| 2003 | 841.5 |
| 2004 | 841.5 |
| 2005 | 487.1 |
| 2006 | 589.4 |
| 2007 | 589.4 |
| 2008 | 589.4 |
| 2009 | 582.5 |
| 2010 | 541.5 |
| 2011 | 480.1 |
| 2012 | 480.3 |
| 2013 | 483.3 |
| 2014 | 483.3 |
| 2015 | 507.3 |
| 2016 | 487.3 |
| 2017 | 487.3 |