Year	% of total primary
1989	28.5197296142578
1990	28.778190612793
1991	31.3593692779541
1992	22.0315494537354
1993	17.0809593200684
1994	15.3385601043701
1995	13.5531702041626
1996	12.6796998977661
1997	12.2864398956299
1999	11.1286697387695
2000	10.0580902099609
2001	9.32736968994141
2002	8.25638008117676
2003	7.95159006118774
2004	7.76913022994995
2005	7.91021013259888
2006	8.16114044189453
2007	8.75984954833984
2008	9.06972026824951
2009	8.9891300201416
2010	7.88158988952637
2011	7.34626007080078
2012	8.01058959960938
2014	8.8096399307251
2015	9.89013004302979
2017	10.6227798461914
2018	10.6426496505737