Year	% of total primary
1970	15.887749671936
1971	16.6564998626709
1972	16.5892601013184
1973	16.0377597808838
1974	15.575909614563
1975	15.2253999710083
1976	14.8505001068115
1977	14.6925497055054
1978	14.6565799713135
1979	14.4120798110962
1980	14.3289098739624
1981	14.3877801895142
1982	14.3641796112061
1983	14.3414602279663
1984	14.2271699905396
1985	14.3622102737427
1986	14.2468099594116
1987	14.145959854126
1988	13.9932203292847
1989	14.2227802276611
1990	14.5085496902466
1991	14.3452396392822
1992	14.5915203094482
1993	15.0406198501587
1994	15.3317604064941
1995	15.4565696716309
1996	15.6827697753906
1997	16.0755004882812
1998	10.3415298461914
1999	9.35050964355469
2000	9.73779964447021
2001	10.5997295379639
2002	10.8739995956421
2003	11.0661697387695
2004	11.4333095550537
2005	12.0497598648071
2006	12.5804004669189
2007	13.6155700683594
2008	14.3034896850586
2009	15.1075401306152
2010	15.8721199035645
2011	16.5754909515381
2012	16.867359161377
2013	17.335090637207
2014	17.7231006622314
2015	18.3176593780518
2016	18.7317008972168
2017	19.794059753418
2018	20.2059097290039
2019	20.6222705841064
2020	20.8228492736816
2021	21.0158996582031
2022	21.0955295562744