Year	% of total primary
1981	3.96782994270325
1982	4.24294996261597
1983	4.35852003097534
1984	4.39489984512329
1985	4.46784019470215
1986	4.49254989624023
1987	4.60435009002686
1988	4.71396017074585
1989	4.80184984207153
1990	4.79161977767944
1991	4.80971002578735
1992	4.74174976348877
1998	6.04674005508423
1999	4.62482976913452
2000	4.68767023086548
2001	4.78385019302368
2002	4.8744101524353
2003	4.91354990005493
2004	5.0281400680542
2005	5.25651979446411
2006	5.33805990219116
2007	5.33187007904053
2008	4.9762601852417
2009	5.06421995162964
2010	5.03659009933472
2011	5.0730299949646
2012	7.05603981018066
2013	10.6499395370483
2014	13.9012498855591
2015	17.8016204833984
2016	20.419340133667
2017	24.2163200378418
2018	28.4112701416016
2019	31.8819599151611
2020	34.1717414855957
2021	35.4554100036621
2022	36.8416213989258