Year % of population 1981 56.4 1982 55.7 1983 54.5 1984 53.8 1985 53.2 1986 52.8 1987 52.7 1988 52.1 1989 51.9 1990 51.7 1991 51 1992 50.3 1993 50.2 1994 49.7 1995 49.3 1996 48.6 2002 47.1 2003 46.4 2004 45.3 2005 44.3 2006 43.4 2007 42.4 2008 41.7 2009 40.7 2010 39.2 2011 37.8 2012 37 2013 36.3 2014 35.8 2015 35.2 2016 34.8 2017 33.6 2018 32.3 2019 32.5 2020 33.5 2021 32.7 2022 31.9