Year % 1997 30.8351 1999 30.97656 2000 21.20899 2001 21.1912 2002 21.29445 2003 21.06827 2004 21.88506 2005 21.56448 2006 11.30313 2007 20.80717 2008 19.9711 2009 10.80026 2010 19.00199 2012 11.15025 2013 11.15025 2018 5.775424 2019 7.132798 2020 7.188456 2021 6.995087