Year	% of total primary
1970	15.0300397872925
1971	15.8198099136353
1972	15.9799900054932
1973	15.9996500015259
1974	15.4421997070312
1975	14.4990797042847
1976	14.5267896652222
1977	14.2574195861816
1978	14.0592803955078
1979	13.8800001144409
1980	13.8516902923584
1981	13.7698602676392
1982	13.6612396240234
1983	13.6115102767944
1984	13.5373497009277
1985	13.5343904495239
1986	13.5026397705078
1987	13.4648399353027
1988	13.5339298248291
1989	13.5341396331787
1990	13.677490234375
1991	13.7894897460938
1992	13.9210596084595
1993	14.1303300857544
1994	14.3848600387573
1995	14.536979675293
1996	14.6146297454834
1997	14.8165502548218
1998	14.9444198608398
1999	15.0874300003052
2000	15.054479598999
2001	15.2388896942139
2002	14.9608402252197
2003	15.8603801727295
2004	16.7555904388428
2005	17.6319599151611
2006	18.1751003265381
2007	19.0090198516846
2008	19.4242897033691
2009	20.279260635376
2010	20.9754905700684
2011	21.5767002105713
2012	22.2748394012451
2013	22.790470123291
2014	23.2765598297119
2015	23.2428302764893
2016	22.8778190612793
2017	23.3689193725586
2018	25.8226795196533
2019	25.805570602417
2020	26.4407997131348
2021	26.4003505706787