Year % 1990 14.1141141141141 1991 13.8297872340426 1992 13.7254901960784 1993 13.6741479634248 1994 13.7875659554944 1995 14.1093011035208 1996 14.7518749002713 1997 15.8090706934892 1998 17.1303022786066 1999 18.2960997743671 2000 18.7455764888275 2001 18.6943753222588 2002 19.5024686669199 2003 21.1432102205611 2004 22.8908554572271 2005 24.5127664320915 2006 26.0460945456062 2007 27.5287488324376 2008 28.8848626244074 2009 30.0722053505047 2010 31.1231567589786 2011 32.050907894015 2012 32.8932066403175 2013 33.6923900099772 2014 34.445909334002 2015 35.1344539108618 2016 35.7102365679762 2017 36.1643504257675 2018 36.5343538793632 2019 36.8131557098649 2020 36.9881759730169 2021 37.0516100539857 2022 36.9967460024094