Year	% of total
1990	5.7054482075242134
1991	5.764097428445722
1992	5.957395957132077
1993	6.1702745815402285
1994	6.36395026551802
1995	6.488707559858513
1996	6.895372589755472
1997	7.101085949840035
1998	6.691508862106236
1999	7.662363423460657
2000	7.304436545526119
2001	7.630001157750563
2002	7.279683099416486
2003	7.136326609411092
2004	6.697517075705137
2005	6.364545093613311
2006	6.5630196770440365
2007	6.762983233554139
2008	6.973819511674804
2009	6.923369825394207
2010	6.978846331944331
2011	7.175348029290858
2012	7.450111570959314
2013	7.621893179570721
2014	7.879089809662372
2015	8.119948150873453
2016	8.365450602355024