Year	% of total primary
1987	6.27138996124268
1988	6.47467994689941
1989	6.29601001739502
1991	7.3132700920105
1992	10.1600103378296
1993	9.71982955932617
1994	10.6716203689575
1995	10.852970123291
1996	10.9895401000977
1997	13.1279697418213
1999	13.3210296630859
2000	17.4118995666504
2001	17.3498191833496
2002	18.2755508422852
2003	15.9452896118164
2004	17.9975299835205
2005	20.5224304199219
2006	15.1821002960205
2007	16.0841598510742
2008	17.2910995483398
2009	17.9599094390869
2011	19.2859497070312
2012	22.0874004364014
2013	23.1213092803955
2014	23.2262001037598
2015	25.2703495025635
2016	25.2808990478516
2017	25.814920425415
2018	27.8528099060059
2020	29.7873802185059
2021	30.8761291503906
2022	28.4046802520752