Year	% of total primary
1971	13.8902196884155
1972	13.946439743042
1973	14.0801496505737
1974	14.0572395324707
1975	14.0538997650146
1976	14.0688495635986
1977	14.1592597961426
1981	14.5029897689819
1982	14.4981698989868
1983	14.6228799819946
1984	14.8169898986816
1985	15.0785799026489
1986	15.0706596374512
1987	15.0333003997803
1988	14.9598598480225
1989	14.8318004608154
1990	14.8107900619507
1991	14.7510204315186
1992	14.734450340271
1993	14.718150138855
1994	14.4518299102783
1996	14.3434495925903
1997	14.5364103317261
1999	14.5762395858765
2000	14.5563201904297
2001	14.5684299468994
2002	14.5685396194458
2003	14.5637903213501
2004	14.7098903656006
2005	15.0542297363281
2006	14.950119972229
2007	14.875189781189
2008	14.9552001953125
2009	14.8652095794678
2010	14.826979637146
2011	14.7783498764038
2012	14.8431701660156
2013	14.6612195968628
2014	14.6520795822144
2015	14.644359588623
2016	14.7853298187256
2017	14.9383897781372
2018	15.0481901168823
2019	15.1189699172974
2020	15.0656995773315
2021	15.0695104598999
2022	15.1802701950073