Year	% of total primary
1971	0.437990009784698
1972	0.397419989109039
1973	0.432000011205673
1974	0.468840003013611
1975	0.45116001367569
1976	0.447539985179901
1981	0.580749988555908
1982	0.62747997045517
1984	0.703580021858215
1985	0.752629995346069
1986	0.842350006103516
1987	0.894720017910004
1988	0.960189998149872
1989	1.06406998634338
1990	1.10721004009247
1991	1.16375005245209
1992	1.23331999778748
1993	1.18454003334045
1994	1.28143000602722
1995	1.38411998748779
1996	1.45533001422882
1998	1.44826996326447
1999	1.46184003353119
2000	1.50569999217987
2001	1.58157002925873
2002	1.66167998313904
2003	1.75697994232178
2004	1.87812995910645
2005	1.93575000762939
2007	2.20408010482788
2008	2.24193000793457
2009	2.26187992095947
2010	2.30656003952026
2011	2.36338996887207
2012	2.4502100944519
2013	2.71956992149353
2014	2.85924005508423
2015	3.05572009086609
2016	3.19534993171692
2017	3.34069991111755
2018	3.43216991424561
2019	3.54770994186401
2020	3.73695993423462
2021	3.82236003875732