Year % 1991 1.054908 1992 15.98208 1994 18.95681 1995 21.93877 1996 18.64142 1997 19.57094 1998 19.27937 1999 19.58878 2000 21.74633 2001 21.75531 2002 22.35183 2003 21.91409 2004 20.15037 2005 20.94407 2006 18.76006 2007 41.47353 2008 41.77643 2009 41.64028 2010 19.47391 2011 16.46287 2012 0.4976864 2013 16.86049 2014 16.72037 2015 0.5578644 2016 0.5526702 2017 8.507753 2018 0.2472499 2019 0.2639208 2020 0.1763467 2021 5.763388