| Year | Value | | 2021 | 3.8431543093933 | | 2020 | -2.4052860315899 | | 2019 | 7.9383303804684 | | 2018 | 10.753657527194 | | 2017 | 7.4212203216041 | | 2016 | 7.9951796368971 | | 2015 | 7.216453826501 | | 2014 | 3.4347986640803 | | 2013 | 6.762259009102 | | 2012 | 7.8903921802331 | | 2011 | 8.510394343354 | | 2010 | 4.4349388503724 | | 2009 | 0.41041596175511 | | 2008 | 14.038197895948 | | 2007 | 10.892426283183 | | 2006 | 11.300249196278 | | 2005 | 13.691716665201 | | 2004 | 9.9522261486346 | | 2003 | 9.1330140454951 | | 2002 | 5.5231585880723 | | 2001 | 7.2426327965869 | | 2000 | 5.7400929349577 | | 1999 | 11.18274076166 | | 1998 | 1.9558077771398 | | 1997 | 8.1481930117518 | | 1996 | 4.9660621384425 |
|