Year	% of total
1990	2.817099035861767
1991	2.915750723032937
1992	2.7880261252344383
1993	3.0145114160240807
1994	2.990607974267967
1995	2.943525485300485
1996	3.334229634158249
1997	3.2864910953467135
1998	3.5822243502652613
1999	3.3831876859487306
2000	3.730318476652165
2001	3.821624321222178
2002	3.714481696698193
2003	3.6075555347163437
2004	3.4601691123086473
2005	3.2327642653580835
2006	3.235691871722407
2007	3.141125538102142
2008	2.8899320269521294
2009	2.4650362786549405
2010	2.59663732681038
2011	2.3504680389879233
2012	2.4876167368489916
2013	2.254165737386326
2014	2.287090381191277
2015	2.2680883331348682
2016	2.017769600867767