| Year | |
|---|---|
| 1991 | 0.0 |
| 1992 | 0.0 |
| 1993 | 0.0 |
| 1994 | 0.0 |
| 1995 | 0.0 |
| 1996 | 0.0 |
| 1997 | 0.0 |
| 1998 | 0.0 |
| 1999 | 408.2 |
| 2000 | 680.2 |
| 2001 | 1,205.8 |
| 2002 | 1,049.0 |
| 2003 | 678.4 |
| 2004 | 918.3 |
| 2005 | 1,126.7 |
| 2006 | 1,531.6 |
| 2007 | 1,432.7 |
| 2008 | 1,310.4 |
| 2009 | 850.2 |
| 2010 | 1,005.1 |
| 2011 | 806.8 |
| 2012 | 926.6 |
| 2013 | 1,195.5 |
| 2014 | 1,151.1 |