Year Number 1987 25.96154 1988 26.73077 1989 26.51852 1990 25.43333 1991 25.65372 1992 25.25234 2000 23.20826 2001 23.81876 2002 28.75162 2003 24.48955 2004 19.27998 2005 21.13767 2006 22.46631 2007 22.06239 2008 21.46367 2009 18.84797 2010 18.28517 2011 18.18672 2012 18.82678 2014 19.36105 2017 61.81179