Year	% of total
1990	34.49042196617552
1991	34.177611065391105
1992	35.41711572342241
1993	34.86746499677472
1994	34.499499263690865
1995	33.111475532735895
1996	34.50859564674903
1997	35.00735932789274
1998	32.69583879076902
1999	33.40575781586204
2000	33.703381025687435
2001	31.908414713244447
2002	30.43057558092844
2003	28.592057351566947
2004	27.392958101825524
2005	25.110800105514596
2006	23.198975100190093
2007	21.81718809271164
2008	21.762390271239155
2009	20.599683486975987
2010	20.67680679123113
2011	19.477324614984312
2012	19.622548571463632
2013	19.46166802618397
2014	19.429936320628716
2015	19.919061677550275
2016	19.88044497915761