Year	% of total primary
1974	28.4423809051514
1975	28.1558303833008
1976	27.4740104675293
1977	26.8516101837158
1978	26.2995700836182
1979	25.621280670166
1980	25.5028495788574
1981	25.2948207855225
1982	24.4276695251465
1983	23.7908802032471
1984	23.9165592193604
1985	23.7413196563721
1986	23.789529800415
1987	23.9959392547607
1988	24.427209854126
1989	24.6468296051025
1990	25.5984497070312
1991	26.5899791717529
1992	27.7395496368408
1993	28.448169708252
1994	28.5147094726562
1995	28.3154106140137
1996	27.9123802185059
1997	27.5169906616211
1998	27.4119606018066
1999	27.5804195404053
2000	27.4466705322266
2001	27.0103092193604
2002	26.5224800109863
2003	26.7750701904297
2004	27.4986991882324
2005	27.6624298095703
2006	27.7085609436035
2007	29.1859092712402
2008	31.1084594726562
2009	30.8386001586914
2010	27.5339107513428
2011	26.1434707641602
2012	25.5900897979736
2013	23.2786293029785
2014	22.2334594726562
2015	21.1592998504639
2016	19.719310760498
2017	19.3807201385498
2018	18.1082992553711
2019	20.2923908233643
2020	20.4689197540283
2021	19.8246097564697
2022	20.7221698760986