Year	% of total primary
1970	12.5243902206421
1971	12.4787902832031
1972	12.2093496322632
1973	12.4749202728271
1974	12.3535404205322
1975	11.9172601699829
1976	12.0587797164917
1977	11.7559003829956
1978	11.7000999450684
1979	11.5802001953125
1980	11.5470504760742
1981	11.6267995834351
1982	11.5445499420166
1983	11.4730100631714
1984	11.3694200515747
1985	11.7210597991943
1986	11.8027400970459
1987	11.9103403091431
1988	11.9939098358154
1989	12.1886701583862
1990	12.2651596069336
1991	12.4657001495361
1992	12.785590171814
1993	12.902979850769
1994	13.1074695587158
1995	13.1258401870728
1996	13.2435598373413
1997	13.6201601028442
1998	13.8033599853516
1999	13.864649772644
2000	13.9147796630859
2001	13.988169670105
2002	14.2375402450562
2003	14.4595804214478
2004	14.8614101409912
2005	15.2837896347046
2006	15.6536703109741
2007	16.0169792175293
2008	16.6305999755859
2009	16.8727607727051
2010	17.209529876709
2011	17.5947399139404
2012	18.1079692840576
2013	18.3356609344482
2014	18.8279495239258
2015	19.1238498687744
2016	19.4115104675293
2017	19.5564308166504
2018	19.6781902313232
2019	19.9062595367432
2020	19.7296504974365
2021	18.697660446167
2022	18.9642696380615