Year | Value | 2022 | 19.9 | 2021 | 20.8 | 2020 | 22.3 | 2019 | 19.7 | 2018 | 19.6 | 2017 | 21 | 2016 | 23.7 | 2015 | 22.6 | 2014 | 22.6 | 2013 | 23.3 | 2012 | 27 | 2011 | 32.2 | 2010 | 34.1 | 2009 | 35.7 | 2008 | 37.2 | 2007 | 40.3 | 2006 | 43.8 | 2005 | 39.1 | 2004 | 42.8 | 2003 | 44.7 | 2002 | 51.7 | 2001 | 39.5 | 1999 | 41.4 | 1997 | 38 | 1995 | 43.6 | 1990 | 21.8 |
|