Year	% of total primary
1970	15.670129776001
1971	18.8750705718994
1972	17.959939956665
1973	17.6012992858887
1974	15.5465297698975
1975	13.5947704315186
1976	13.9576902389526
1977	13.9678497314453
1978	13.9065399169922
1979	13.5470504760742
1980	13.486180305481
1981	13.4666700363159
1982	13.5999898910522
1983	13.5289497375488
1984	13.3989601135254
1985	13.3620796203613
1986	13.1755199432373
1987	13.0525703430176
1988	13.0965795516968
1989	13.0008602142334
1990	13.1718997955322
1991	13.2851896286011
1992	13.6337203979492
1993	13.8034496307373
1994	13.9211397171021
1995	14.4591903686523
1996	14.6655902862549
1997	14.7187204360962
1998	14.9231901168823
1999	15.0379104614258
2000	15.083589553833
2001	15.1938695907593
2002	15.0417203903198
2003	14.9453601837158
2004	15.1133403778076
2005	15.3144302368164
2006	15.0286302566528
2007	14.9729795455933
2008	14.7308101654053
2009	15.1435804367065
2010	15.2632503509521
2011	15.8724603652954
2012	15.8015203475952
2013	15.6016101837158
2014	15.2936096191406
2015	15.1805801391602
2016	15.1497898101807
2017	15.4220600128174
2018	16.1647396087646
2019	16.0173606872559
2020	15.9474000930786
2021	16.2396106719971
2022	16.2787704467773