Year % 1977 2.8 1978 2.7 1979 2.7 1980 3 1981 3.1 1982 3.4 1983 3.2 1984 3 1986 3 1987 2.4 1989 3.1 1991 3 1993 2 1995 2.1 1998 1.8 2000 2.1 2002 2.2 2003 2.3 2004 2.4 2005 2.4 2006 2.5 2007 2.5 2008 2.4 2009 2.3 2010 2.1 2011 2.1 2012 2 2013 2 2014 2 2015 1.7 2016 1.9 2017 1.9 2018 1.9 2019 2.1 2020 2.1 2021 2.3