Year	% of total primary
1971	21.8591899871826
1980	19.7169704437256
1981	20.379280090332
1983	21.7080593109131
1984	22.536750793457
1985	23.4030704498291
1986	23.9973392486572
1987	24.2985000610352
1988	24.559139251709
1989	24.7782001495361
1990	24.8734703063965
1991	24.9442596435547
1992	24.9699306488037
1993	25.0548305511475
1994	25.3534908294678
1995	25.7620601654053
1996	26.0129299163818
1997	26.3382301330566
1998	26.6022090911865
1999	26.8631496429443
2000	27.21875
2001	27.6041793823242
2002	27.9659099578857
2003	28.302209854126
2004	28.676549911499
2005	29.0979404449463
2006	29.4548206329346
2007	29.8456592559814
2008	30.2628593444824
2009	30.5496006011963
2010	30.8721504211426
2011	31.081579208374
2012	31.0847301483154
2013	31.0443096160889
2014	30.9073696136475
2015	30.4306697845459
2016	30.0825901031494
2017	29.8130798339844
2018	29.6970195770264
2019	29.5387496948242
2020	29.6109008789062
2021	30.1743602752686
2022	30.8816394805908