Year Number 1996 0.688413977622986 1998 0.716092944145203 2000 0.655752897262573 2002 0.702703297138214 2003 0.544806301593781 2004 0.433262318372726 2005 0.389575779438019 2006 0.31153592467308 2007 0.274766087532043 2008 0.417219996452332 2009 0.399278730154037 2010 0.317414134740829 2011 0.498547106981277 2012 0.534359633922577 2013 0.613574981689453 2014 0.65126621723175 2015 0.614114046096802 2016 0.81918078660965 2017 0.767983138561249 2018 0.77433305978775 2019 0.808057069778442 2020 0.876260638237 2021 0.799450576305389 2022 0.836642742156982