Year	% of total primary
1999	19.2262992858887
2000	19.4163398742676
2001	19.6412696838379
2002	18.8139400482178
2003	20.1193408966064
2004	21.5433597564697
2005	23.0135192871094
2006	23.9682502746582
2007	24.903959274292
2008	25.8383293151855
2009	27.169059753418
2010	28.1757202148438
2011	29.2757892608643
2012	30.436429977417
2013	31.5425796508789
2014	32.7561683654785
2015	32.5441284179688
2016	31.3102207183838
2017	32.2637405395508
2018	37.8465995788574
2019	38.0147895812988
2020	39.1973686218262
2021	39.2008399963379