Year	% of total primary
1972	2.47008991241455
1973	2.38680005073547
1974	2.24215006828308
1975	2.10195994377136
1976	2.00463008880615
1977	2.02288007736206
1978	2.04555010795593
1979	2.03166007995605
1980	2.01325011253357
1981	1.99879002571106
1982	2.01605010032654
1983	2.03345990180969
1984	2.10052990913391
1985	2.09848999977112
1986	2.13562989234924
1987	2.21483993530273
1988	2.29277992248535
1989	2.32236003875732
1990	2.43367004394531
1991	2.40605998039246
1992	2.49121999740601
1993	2.51486992835999
1994	2.57061004638672
1995	2.72586989402771
1996	2.9556999206543
1997	3.13609004020691
1998	3.35227990150452
1999	3.59672999382019
2000	3.81908988952637
2001	4.0588698387146
2002	4.42439985275269
2003	4.8362398147583
2004	5.03747987747192
2005	5.48699998855591
2006	5.89723014831543
2007	6.26574993133545
2008	6.80471992492676
2009	7.17033004760742
2010	7.54171991348267
2011	7.94568014144897
2012	8.32783031463623
2013	8.6694803237915
2014	9.12252044677734
2015	9.45718955993652
2016	9.637619972229
2017	9.76105976104736
2018	10.0735197067261
2019	10.3465700149536
2020	10.5598402023315
2021	10.3387699127197
2022	10.2790403366089