| Year | |
|---|---|
| 1997 | 61.0 |
| 1998 | 75.9 |
| 1999 | 65.5 |
| 2000 | 70.7 |
| 2001 | 67.2 |
| 2002 | 70.8 |
| 2003 | 76.7 |
| 2004 | 81.7 |
| 2005 | 100.8 |
| 2006 | 105.6 |
| 2007 | 112.3 |
| 2008 | 117.1 |
| 2009 | 93.5 |
| 2010 | 100.1 |
| 2011 | 116.6 |
| 2012 | 128.0 |
| 2013 | 127.5 |
| 2014 | 126.4 |
| 2015 | 126.1 |
| 2016 | 127.2 |
| 2017 | 127.8 |
| 2018 | 126.3 |
| 2019 | 110.5 |
| 2020 | 64.0 |
| 2021 | 42.0 |
| 2022 | 41.3 |
| 2023 | 43.5 |
| 2024 | 44.7 |