Year	% of total primary
1970	9.54456043243408
1971	9.85976982116699
1972	9.65326976776123
1973	9.444580078125
1974	9.10344982147217
1975	8.6600399017334
1976	8.58096027374268
1977	8.50967025756836
1978	8.46329021453857
1979	8.38906955718994
1980	8.37609958648682
1981	8.37977027893066
1982	8.42875003814697
1983	8.47130966186523
1984	8.5042200088501
1985	8.49598026275635
1986	8.49139022827148
1987	8.51395034790039
1988	8.64398956298828
1989	8.77027034759521
1990	8.88770008087158
1991	8.90386962890625
1992	9.04442977905273
1993	9.17531967163086
1994	9.29374027252197
1995	9.50409030914307
1996	9.6173095703125
1997	9.70592021942139
1998	9.81935024261475
1999	9.98223972320557
2000	10.1061201095581
2001	10.3308601379395
2002	10.3934297561646
2003	11.06369972229
2004	11.439040184021
2005	12.1034603118896
2006	12.5818300247192
2007	13.1764497756958
2008	13.5664396286011
2009	14.1715497970581
2010	14.6982297897339
2011	15.3248195648193
2012	15.8250703811646
2013	16.2516098022461
2014	16.6152305603027
2015	16.7797603607178
2016	16.7677803039551
2017	17.2001895904541
2018	18.4091300964355
2019	18.4066505432129
2020	18.703010559082
2021	18.6984691619873
2022	19.0013408660889