Year | |
---|---|
1997 | 19.1 |
1998 | 21.2 |
1999 | 17.6 |
2000 | 23.9 |
2001 | 23.2 |
2002 | 28.7 |
2003 | 24.5 |
2004 | 24.6 |
2005 | 26.5 |
2006 | 25.5 |
2007 | 26.9 |
2008 | 27.9 |
2009 | 28.3 |
2010 | 31.4 |
2011 | 32.1 |
2012 | 31.5 |
2013 | 34.5 |
2014 | 32.0 |
2015 | 30.9 |
2016 | 26.0 |
2017 | 20.8 |
2018 | 15.4 |
2019 | 12.2 |
2020 | 4.3 |
2021 | 2.9 |
2022 | 2.1 |
2023 | 1.3 |
2024 | 1.0 |