| 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 | 554.0 |
| 2000 | 823.7 |
| 2001 | 1,401.3 |
| 2002 | 1,350.3 |
| 2003 | 816.8 |
| 2004 | 1,248.2 |
| 2005 | 1,469.4 |
| 2006 | 1,848.3 |
| 2007 | 1,994.8 |
| 2008 | 1,561.6 |
| 2009 | 1,070.6 |
| 2010 | 1,246.6 |
| 2011 | 1,087.3 |
| 2012 | 1,262.6 |
| 2013 | 1,503.9 |
| 2014 | 1,414.5 |