Year Number 1996 1.73311007022858 1998 1.91423785686493 2000 2.1970431804657 2002 2.19461417198181 2003 2.22752285003662 2004 2.167231798172 2005 2.30135536193848 2006 2.17291116714478 2007 2.19767022132874 2008 2.32725143432617 2009 2.03152012825012 2010 1.93496966362 2011 1.93282318115234 2012 1.87803149223328 2013 1.90477347373962 2014 1.82383286952972 2015 1.89814746379852 2016 1.90391433238983 2017 1.79447102546692 2018 1.80538582801819 2019 1.67087435722351 2020 1.667649269104 2021 1.760617852211 2022 1.56752812862396