Year % 1990 3.18493447886835 1991 4.16010085092972 1992 5.19512269657428 1993 6.21367284804871 1994 7.18024666138958 1995 8.08068751492003 1996 8.91385599135408 1997 9.68114207556847 1998 10.3864586519833 1999 11.0327170386585 2000 11.536935949984 2001 11.9450491155542 2002 12.3310002657925 2003 12.764241592313 2004 13.2144756081351 2005 13.6757634723317 2006 14.1468800049758 2007 14.621351050717 2008 15.0780852763856 2009 15.5229584668128 2010 16.0307742764219 2011 16.4971404956474 2012 16.9082819003875 2013 17.3024628014366 2014 17.7334798701381 2015 18.1519261667227 2016 18.488992457227 2017 18.8037080457825 2018 19.1321805427755 2019 19.4175791654336 2020 19.6399633622208 2021 19.8071017386532 2022 19.9194374592531