Year	% of total primary
1970	5.84932994842529
1971	27.9932994842529
1972	27.8960494995117
1973	25.506139755249
1975	4.05519008636475
1976	9.13276958465576
1977	10.9220199584961
1978	15.2607402801514
1979	15.2312297821045
1980	14.636269569397
1981	11.2673597335815
1983	11.6278600692749
1984	11.6278600692749
1985	11.0000095367432
1986	10.9183902740479
1987	10.9184103012085
1988	13.2190704345703
1989	13.6003904342651
1990	15.1730604171753
2005	41.6517715454102
2006	42.6572914123535
2007	42.4510192871094
2008	40.3315010070801
2009	40.9504508972168
2017	21.3980407714844
2018	23.9035205841064