Year	% of total
1990	4.93206556158184
1995	5.39840035332182
2000	6.15546033534561
2005	6.69589541313482
2010	7.44571907834857
2011	6.34526793133691
2012	6.15199768484813
2013	5.42807652388694
2014	4.89416329865162
2015	4.86864840263034
2016	4.65848492451664
2017	4.69912222911881