Year	% of total
1990	8.429943121344946
1991	8.373650911797544
1992	8.302197071377613
1993	9.850989101802593
1994	13.824419778002017
1995	12.497562292794887
1996	12.417426064568584
1997	12.498076923076923
1998	12.49567606063689
1999	12.910017263884797
2000	14.67344712025563
2001	14.212849781029602
2002	15.237736107778273
2003	13.504838255096608
2004	12.035252819478677
2005	11.578993912774331
2006	10.840531978732015
2007	10.66738034935638
2008	9.287039227158987
2009	8.739677296404523
2010	9.706458872782711
2011	9.104243180190794
2012	8.228018574183608
2013	7.49956347127641
2014	7.8644306544333205
2015	8.705902242927452