Year	% of total primary
1970	15.8543500900269
1971	16.1511192321777
1972	16.6798801422119
1973	16.5970706939697
1974	16.9064598083496
1975	17.3426208496094
1976	17.3166103363037
1981	18.0006103515625
1982	17.925479888916
1984	18.6930294036865
1985	18.6326198577881
1986	18.7714195251465
1987	18.8961601257324
1988	18.8646697998047
1994	20.5174503326416
1996	20.3407402038574
1997	20.942720413208
1998	20.6977996826172
1999	19.5295295715332
2000	19.9244594573975
2001	19.7511100769043
2002	19.5556907653809
2003	19.7878093719482
2004	20.2285404205322
2005	21.0695495605469
2006	21.1949291229248
2007	21.8456401824951
2008	22.6905097961426
2009	23.1661701202393
2010	23.6371002197266
2011	23.9507503509521
2012	24.7365093231201
2013	25.323070526123
2014	25.7752304077148
2015	26.1601905822754
2016	26.3700103759766
2017	26.6536102294922
2018	26.4862899780273
2019	26.080099105835
2020	25.7769393920898
2021	25.1348991394043