Year	% of total primary
1973	33.3697814941406
1974	35.8064193725586
1975	36.2667503356934
1976	37.0647811889648
1981	35.5371704101562
1982	35.3117904663086
1983	35.1843414306641
1984	34.9451713562012
1985	34.5919990539551
1986	34.2195701599121
1987	34.602409362793
1988	33.5722198486328
1989	34.2043609619141
1990	34.5017013549805
1991	34.931568145752
1992	35.4586906433105
1993	35.5057792663574
1994	34.9715805053711
1995	34.7947311401367
1996	34.3538818359375
1997	34.0713806152344
1999	33.482780456543
2000	33.3524703979492
2001	33.4272689819336
2002	33.6029281616211
2003	33.4090194702148
2004	33.4416313171387
2005	33.3871002197266
2006	33.2635688781738
2007	33.0190200805664
2008	32.9160690307617
2009	32.8903617858887
2010	32.7953186035156
2011	32.622200012207
2012	32.5578804016113
2013	31.6780796051025
2014	31.6363792419434
2015	31.516300201416
2016	31.5134906768799
2017	31.447940826416
2018	31.4809494018555
2019	31.5313091278076
2020	31.5429801940918
2021	31.7198600769043