Year	% of total teachers
1999	64.7975082397461
2000	69.1358032226562
2001	64.7239303588867
2003	65.8536605834961
2004	64.83740234375
2005	65.6804733276367
2006	65.1456298828125
2007	65.5367202758789
2008	59.792839050293
2009	51.6562194824219
2010	56.5179405212402
2011	52.8395118713379
2012	56.0956802368164
2013	50.363899230957
2014	45.9039497375488
2015	41.8269195556641
2017	39.7793617248535
2018	41.6094818115234
2019	37.5800018310547