Year	% of total primary
1972	5.89210987091064
1975	5.79948997497559
1976	4.21722984313965
1981	4.16370010375977
1982	4.11633014678955
1983	4.13160991668701
1984	4.13274002075195
1985	4.08936977386475
1986	4.2056097984314
1987	4.19319009780884
1988	3.93547010421753
1990	3.6256000995636
1991	3.31263995170593
1992	15.9851903915405
1993	17.218620300293
1994	17.1203994750977
1995	18.7131099700928
1996	19.4505596160889
1999	21.888240814209
2004	34.7664794921875
2005	37.0346603393555
2006	37.8004302978516
2007	38.4849700927734
2008	39.5875701904297
2009	39.7423095703125
2010	39.8242111206055
2011	38.7733116149902
2013	35.2997093200684
2015	38.4980392456055
2016	36.9445991516113
2017	42.7137298583984
2018	39.934871673584