| Year | Value | | 2021 | 43.272234540527 | | 2020 | 43.194403389497 | | 2019 | 43.126154755746 | | 2018 | 43.051532170657 | | 2017 | 42.978402664197 | | 2016 | 42.90696987014 | | 2015 | 42.534166264324 | | 2014 | 42.531765308686 | | 2013 | 42.541940189643 | | 2012 | 42.540377232022 | | 2011 | 42.534621260657 | | 2010 | 42.532848370149 | | 2009 | 42.35773639957 | | 2008 | 42.180954352347 | | 2007 | 42.005214365627 | | 2006 | 41.828648030596 | | 2005 | 41.667282937195 | | 2004 | 41.49495845968 | | 2003 | 41.316695098262 | | 2002 | 41.140073658106 | | 2001 | 40.961034095167 | | 2000 | 40.78423252879 | | 1999 | 40.543791751917 | | 1998 | 40.301929211306 | | 1997 | 40.053732961968 | | 1996 | 39.810898478709 | | 1995 | 39.56513595047 | | 1994 | 39.320182572778 | | 1993 | 39.074482976165 | | 1992 | 38.824607742648 |
|