Year Number 1996 27.8688526153564 1998 26.7759571075439 2000 30.0546455383301 2002 25.9459457397461 2003 29.1891899108887 2004 25.8706474304199 2005 24.0196075439453 2006 27.3170738220215 2007 25.2427177429199 2008 27.1844654083252 2009 26.7942581176758 2010 25.3588523864746 2011 25.1184825897217 2012 25.5924167633057 2013 17.5355453491211 2014 25 2015 23.8095245361328 2016 25.238094329834 2017 23.8095245361328 2018 21.9047622680664 2019 30.9523811340332 2020 20.4761905670166 2021 25.7142848968506 2022 19.3396224975586