Year % of population 1984 59.3 1985 57.5 1986 56 1987 54.6 1988 52.3 1989 55.5 1990 55 1991 54.1 1992 52.9 1993 51.9 1994 50 1995 48.8 1996 47.6 1997 47.5 1998 47.8 1999 46.8 2000 46.1 2001 45.4 2002 44.5 2003 43.4 2004 42.1 2005 40.9 2006 40.2 2007 39.3 2008 38.7 2009 38 2010 36.8 2011 35.4 2012 34.7 2013 33.2 2014 32.7 2015 32.1 2016 31.9 2017 31.3 2018 30.4 2019 30.3 2020 30.4 2021 30 2022 29.4