Year	% of total primary
1971	16.8004493713379
1972	19.0402202606201
1981	21.498140335083
1983	22.1405792236328
1985	23.0388298034668
1986	22.4610290527344
1995	24.7987899780273
1996	22.0431709289551
1997	23.7974491119385
1998	22.021240234375
2002	24.5922794342041
2004	24.9653491973877
2005	27.5114707946777
2006	26.3132991790771
2007	29.1983203887939
2008	30.1930294036865
2009	30.3800392150879
2010	29.5906105041504
2011	26.1314601898193
2012	28.293909072876
2013	23.7563495635986
2014	24.2296199798584
2015	25.6089706420898
2016	18.753870010376
2018	22.6681098937988
2019	20.3429698944092