Year % 2000 3.7539140866341114 2001 3.645943953828066 2002 3.5385776016740604 2003 3.344144187139219 2004 3.2139495959549764 2005 3.106450681257707 2006 2.968437685013973 2007 2.9029260840889815 2008 2.858234226283585 2009 2.72661394904646 2010 2.5920661310835906 2011 2.464576394034778 2012 2.304515337688609 2013 2.200975261997601 2014 2.098318947608511 2015 2.0034336379703683 2016 1.8984487822404372 2017 1.8266342820263415 2018 1.7330074916665827 2019 1.673022602372439 2020 1.6168702116177047