Year % 1990 54.2857142857143 1991 60.9243697478992 1992 66.6666666666667 1993 68.8102893890675 1994 69.8924731182796 1995 70.046511627907 1996 69.7602474864656 1997 69.1607026675342 1998 68.0525164113786 1999 66.219342896807 2000 63.8272583201268 2001 60.9941318605454 2002 57.751586582049 2003 55.2456839309429 2004 53.4531693472091 2005 52.1739130434783 2006 51.1962653180315 2007 50.467794170565 2008 49.9072356215213 2009 49.4708146247595 2010 49.1535857186827 2011 48.9190398091546 2012 48.7625899280576 2013 48.8885782189291 2014 49.0589198036007 2015 49.2879009716491 2016 49.518479958355 2017 49.7774386366527 2018 49.1343775762572 2019 49.818224463469 2020 49.9658392165794 2021 50.0721821210439 2022 50.1513186338089