Year	% of total
1990	20.76700786862891
1991	18.948911730473792
1992	20.509620720906845
1993	22.967606489992388
1994	21.8625123666847
1995	22.484851757232025
1996	21.761304505534422
1997	22.23323209534027
1998	23.646069298393673
1999	23.62079148430452
2000	22.169440041137157
2001	23.569222823418734
2002	23.975170319751598
2003	23.091473447810085
2004	23.294746560603276
2005	23.808210421675177
2006	24.086677279559794
2007	24.137499521930877
2008	24.79835715018523
2009	25.366847997961067
2010	24.575953286661186
2011	24.194762342043617
2012	24.36151309674595
2013	23.71690862591423
2014	24.782254735694014
2015	25.7528297341258
2016	26.88471354276716