Year	% of total primary
1971	4.89660978317261
1972	4.89041996002197
1973	5.05595016479492
1974	5.10059976577759
1975	5.19200992584229
1976	5.25716018676758
1977	5.39154005050659
1978	5.56356000900269
1979	5.56204986572266
1980	5.55402994155884
1982	5.22397994995117
1983	4.97255992889404
1984	5.60844993591309
1985	5.95805978775024
1986	5.99708986282349
1987	5.86978006362915
1988	6.62947988510132
1989	6.50719022750854
1990	6.61593008041382
1991	6.70850992202759
1992	6.71712017059326
1993	7.23496007919312
1994	7.62482023239136
1995	7.5372200012207
1996	7.4412899017334
1997	7.49642992019653
1998	7.59961986541748
1999	7.52123022079468
2000	7.24882984161377
2001	7.26719999313354
2002	7.09118986129761
2003	7.05033016204834
2004	7.25799989700317
2005	7.61535978317261
2006	7.81108999252319
2007	7.97669982910156
2008	8.14822006225586
2009	8.12570953369141
2014	8.31873989105225
2015	8.14772987365723
2016	8.16901969909668
2017	8.45405006408691
2018	8.9002799987793
2019	9.3357400894165
2020	9.480299949646