Year % of total secondary 1999 16.3686008453369 2000 16.7566299438477 2001 15.9116201400757 2002 16.8232402801514 2003 16.9927196502686 2004 16.8236293792725 2005 17.2018699645996 2006 17.3538303375244 2007 18.0142002105713 2008 18.1215190887451 2009 19.4375896453857 2010 19.7754592895508 2011 20.167049407959 2012 19.1974697113037 2013 19.4050998687744 2014 20.4103603363037 2015 20.6589908599854 2016 20.4636001586914 2017 21.0615501403809 2018 21.4766101837158 2019 21.8395099639893 2020 22.3699607849121 2021 22.4482707977295 2022 22.6793308258057