Year	% of total primary
1971	1.59918999671936
1972	1.31157994270325
1973	1.46138000488281
1974	1.29244005680084
1975	0.621370017528534
1976	0.752619981765747
1977	1.05660998821259
1981	2.59748005867004
1982	3.04153990745544
1983	3.36161994934082
1984	4.05976009368896
1985	4.32663011550903
1986	4.20475006103516
1987	3.95547008514404
1988	3.92711997032166
1989	3.95605993270874
1990	4.13372993469238
1991	4.7790699005127
1992	4.32123994827271
1993	4.62270021438599
1994	4.34929990768433
1995	4.17206001281738
1996	4.22827005386353
1997	4.19233989715576
1999	4.00324010848999
2000	4.07493019104004
2001	4.30881023406982
2002	5.1697301864624
2003	5.42087984085083
2004	5.59200000762939
2005	5.79456996917725
2006	5.93200016021729
2007	6.29229021072388
2008	6.99308013916016
2009	7.27832984924316
2010	7.62325000762939
2011	7.7559700012207
2012	7.71853017807007
2013	7.78819990158081
2014	8.01821994781494
2015	8.71813011169434
2016	8.61736965179443
2017	8.93093967437744
2018	9.53765964508057
2019	10.2286500930786
2020	10.1292295455933
2021	11.1729803085327