Year % 1997 11.610486891385756 1999 13.043478260869566 2000 13.200000000000006 2001 15.306122448979595 2002 15.986394557823123 2003 16.320474777448062 2004 18.75 2005 18.75000000000001 2006 17.99410029498525 2007 17.88856304985337 2008 17.10144927536232 2009 16.95906432748538 2010 13.953488372093023 2011 14.868804664723035 2012 15.294117647058826 2013 16.470588235294127 2014 16.568047337278113 2015 19.648093841642243 2016 19.648093841642247 2017 20.76023391812866 2018 21.637426900584803 2019 22.514619883040933 2020 24.85380116959065 2021 25.364431486880466 2022 25.36873156342184 2023 26.08695652173914