Year	% of total primary
1973	2.66242003440857
1974	2.78362011909485
1975	2.87898993492126
1981	3.3654100894928
1982	3.47883009910583
1983	3.68190002441406
1984	3.69472002983093
1985	3.81353998184204
1986	3.93835997581482
1987	3.79373002052307
1988	3.81770992279053
1989	3.829509973526
1990	3.89258003234863
1991	3.96504998207092
1992	3.9651300907135
1993	4.47704982757568
1994	4.29946994781494
1995	4.33183002471924
1996	4.32009983062744
1997	4.3044900894165
1998	4.27241992950439
1999	4.26362991333008
2000	4.22596979141235
2001	4.2419900894165
2002	4.30754995346069
2003	4.4161901473999
2004	4.5304799079895
2005	4.680260181427
2006	4.85767984390259
2007	5.20894002914429
2008	5.4491400718689
2009	5.63297986984253
2010	5.74029016494751
2011	5.8093900680542
2012	5.87633991241455
2013	5.88486003875732
2014	5.9918098449707
2015	6.14382982254028
2016	6.23875999450684
2017	6.2130298614502
2018	6.25854015350342
2019	6.27003002166748
2020	6.26677989959717
2021	6.3300199508667
2022	6.29622983932495