| Year | |
|---|---|
| 1997 | 224.3 |
| 1998 | 226.9 |
| 1999 | 155.1 |
| 2000 | 171.8 |
| 2001 | 185.5 |
| 2002 | 188.5 |
| 2003 | 207.7 |
| 2004 | 243.7 |
| 2005 | 297.6 |
| 2006 | 274.3 |
| 2007 | 272.0 |
| 2008 | 269.2 |
| 2009 | 249.9 |
| 2010 | 265.1 |
| 2011 | 275.0 |
| 2012 | 286.7 |
| 2013 | 290.2 |
| 2014 | 308.6 |
| 2015 | 292.4 |
| 2016 | 289.3 |
| 2017 | 248.3 |
| 2018 | 253.9 |
| 2019 | 270.8 |
| 2020 | 162.8 |
| 2021 | 171.0 |
| 2022 | 279.2 |
| 2023 | 267.8 |
| 2024 | 272.7 |