Year % of total secondary 1998 11.4826803207397 1999 11.4516000747681 2000 11.5037803649902 2001 11.5864896774292 2002 11.8094396591187 2003 12.0233697891235 2004 11.8660898208618 2005 12.0749101638794 2006 12.3683700561523 2007 12.70578956604 2008 13.0575304031372 2009 13.4355497360229 2010 13.7998695373535 2011 14.0284700393677 2012 14.0585803985596 2013 14.880410194397 2014 14.9591503143311 2015 15.1364498138428 2016 15.2510995864868 2017 15.4620704650879 2018 15.5989398956299 2019 15.7409000396729 2020 15.5884199142456 2021 15.9674196243286 2022 15.9760303497314