Year	% of total primary
1972	5.90023994445801
1973	5.97104978561401
1974	6.02550983428955
1975	6.2189998626709
1976	6.46904993057251
1981	8.84121036529541
1982	6.38956022262573
1983	6.48761987686157
1984	6.92931985855103
1985	8.60826015472412
1986	9.01574039459229
1987	9.38669967651367
1988	9.19223976135254
1989	9.56254005432129
1990	9.74211978912354
1992	10.2221899032593
1993	11.0001201629639
1994	10.9999704360962
1995	10.7001104354858
1996	10.6768798828125
1999	10.7580404281616
2000	10.7780599594116
2002	11.0184097290039
2004	11.7430400848389
2005	12.0841903686523
2006	12.1490697860718
2007	12.1490697860718
2008	13.268030166626
2009	13.4808197021484
2010	13.7287302017212
2011	14.441370010376
2012	14.989239692688
2013	14.8636598587036
2014	15.281590461731
2015	15.6517295837402
2016	16.2836208343506
2017	16.5943202972412
2018	17.0684204101562
2019	17.3794193267822
2020	17.727689743042
2021	18.0379009246826
2022	18.3404598236084