Year Number 1996 22.8723411560059 1998 23.9361705780029 2000 24.8677253723145 2002 28.0423278808594 2003 34.6733665466309 2004 43.6893196105957 2005 40.7766990661621 2006 40.0966186523438 2007 39.613525390625 2008 35.5769233703613 2009 31.7535552978516 2010 40.7582931518555 2011 50.2369651794434 2012 51.6587677001953 2013 38.8625602722168 2014 60.9523811340332 2015 60.9523811340332 2016 57.1428565979004 2017 50.9523811340332 2018 41.5094337463379 2019 37.2641525268555 2020 48.113208770752 2021 50.4716987609863 2022 51.4150924682617