Year Number 1996 0.703103303909302 1998 0.673875689506531 2000 0.687808454036713 2002 0.708452701568604 2003 0.724850833415985 2004 0.72966194152832 2005 0.738931596279144 2006 0.624208450317383 2007 0.693163931369781 2008 0.678534626960754 2009 0.677096426486969 2010 0.693299531936646 2011 0.646594107151031 2012 0.65330559015274 2013 0.652431309223175 2015 0.498630166053772 2016 0.51005220413208 2017 0.480442553758621 2018 0.480384886264801 2019 0.491095125675201 2020 0.52329158782959 2021 0.495514720678329 2022 0.458686977624893