Year	% of total primary
1970	29.313440322876
1971	28.9251708984375
1972	28.9338397979736
1973	26.8190898895264
1974	27.8853397369385
1975	27.8349990844727
1980	25.9494590759277
1981	24.8121204376221
1982	23.475959777832
1983	22.3474292755127
1984	23.2445297241211
1985	23.1547698974609
1986	23.0640602111816
1987	23.3573894500732
1988	23.7092800140381
1989	24.2980098724365
1991	24.3239402770996
1992	24.2388496398926
1993	24.3621692657471
1994	24.2029094696045
1995	23.9602909088135
1996	24.0839900970459
1997	23.6678791046143
1998	23.5508193969727
1999	23.8349208831787
2000	23.9350204467773
2001	24.0354995727539
2002	24.1973209381104
2004	24.9005794525146
2005	25.0659599304199
2006	25.6254806518555
2007	26.1151599884033
2008	26.537109375
2009	27.2425804138184
2010	27.5035800933838
2011	28.057689666748
2012	28.8461208343506
2013	29.6781806945801
2014	30.6201190948486
2015	31.4700908660889
2016	32.4861297607422
2017	33.486759185791
2018	34.6232795715332
2019	35.7307815551758
2020	36.928279876709
2021	37.2035789489746