Year % 1988 56.80887 1989 19.58264 1990 24.59278 1992 23.17178 1995 25.17136 1996 27.46733 1997 25.96685 1998 29.53655 1999 26.96253 2000 28.46002 2001 27.84026 2002 29.2902 2003 30.34329 2004 28.50312 2005 30.18512 2006 29.07491 2007 25.42474 2008 31.58838 2009 31.90171 2010 32.61803 2011 32.85232 2012 31.68212 2013 31.27846 2014 22.58227 2015 21.66957 2016 33.14062 2017 20.96731 2018 19.27802 2020 17.96984 2021 16.92291