Year	% of total primary
1970	12.1399803161621
1971	12.0954504013062
1972	11.8217496871948
1973	12.0610599517822
1974	11.9455795288086
1975	11.5352401733398
1976	11.6792697906494
1977	11.4168996810913
1978	11.3872604370117
1979	11.3021202087402
1980	11.2984895706177
1981	11.398509979248
1982	11.3381500244141
1983	11.2824001312256
1984	11.2047500610352
1985	11.5707302093506
1986	11.6715497970581
1987	11.7944803237915
1988	11.8928298950195
1989	12.0915298461914
1990	12.1760902404785
1991	12.3739795684814
1992	12.6864099502563
1993	12.8000402450562
1994	12.9955196380615
1995	13.0127096176147
1996	13.1176900863647
1997	13.4754104614258
1998	13.6593198776245
1999	13.7248697280884
2000	13.7783699035645
2001	13.8590803146362
2002	14.1119804382324
2003	14.3390502929688
2004	14.7385702133179
2005	15.1575298309326
2006	15.5191097259521
2007	15.8817195892334
2008	16.4865093231201
2009	16.7241191864014
2010	17.0489807128906
2011	17.4347896575928
2012	17.9414901733398
2013	18.1693000793457
2014	18.6506900787354
2015	18.9418697357178
2016	19.2240295410156
2017	19.359899520874
2018	19.4712791442871
2019	19.6881408691406
2020	19.5070400238037
2021	18.4916496276855
2022	18.7559795379639