Year	% of total teachers
2006	74.2034072875977
2007	72.5079727172852
2008	69.4109268188477
2009	65.0842208862305
2010	66.5117797851562
2011	62.9699096679688
2012	64.3282775878906
2013	59.8679389953613
2014	58.322208404541
2015	57.943431854248
2016	58.8744888305664
2017	58.395378112793
2018	59.1368217468262
2019	58.120418548584