Year	% of total primary
1973	4.8674898147583
1974	5.03406000137329
1975	4.84973001480103
1976	3.26208996772766
1981	7.00584983825684
1982	7.26302003860474
1983	6.93510007858276
1984	7.12140989303589
1985	6.71306991577148
1986	7.28568983078003
1987	7.15009021759033
1990	6.07862997055054
1991	6.66997003555298
1992	7.74982976913452
1993	7.76679992675781
1994	7.84327983856201
1999	9.39268016815186
2000	9.64529991149902
2001	9.96100997924805
2002	10.4913597106934
2003	10.5361299514771
2004	10.4957799911499
2005	10.5525302886963
2006	10.8506002426147
2007	11.0786800384521
2008	10.9452896118164
2009	11.521900177002
2010	11.806170463562
2011	12.0226402282715
2012	12.0271501541138
2013	11.9357299804688
2014	12.0751399993896
2015	12.4391098022461
2016	12.9569902420044
2017	12.9030599594116
2018	12.712739944458
2019	12.786190032959
2020	12.784649848938
2021	12.9321804046631