Year	% of total primary
1970	18.4893398284912
1971	19.9756603240967
1972	19.1352291107178
1973	20.1663799285889
1974	17.9216194152832
1980	16.3711700439453
1981	14.7914199829102
1982	18.7141895294189
1983	14.7239398956299
1984	14.3531503677368
1985	15.3827800750732
1986	14.5543699264526
1987	15.1887302398682
1988	15.446439743042
1989	15.5692501068115
1990	16.1866092681885
1991	16.3229999542236
1992	16.210880279541
1993	16.6080207824707
1994	16.4237403869629
1995	16.0593395233154
1996	15.5443296432495
1998	14.6502704620361
2000	14.000340461731
2001	12.6550197601318
2002	12.8789796829224
2003	12.4431104660034
2004	12.9777002334595
2005	13.1357803344727
2006	14.0354900360107
2007	14.3384599685669
2008	15.1001195907593
2009	15.8334999084473
2010	16.1419792175293
2011	16.49169921875
2012	17.0020999908447
2013	17.3358592987061
2014	17.813159942627
2015	17.9831104278564
2016	18.4405708312988
2017	17.8315505981445
2018	18.1444206237793
2019	17.0625190734863
2020	16.8074398040771
2021	16.4589195251465