Year	% of total
1992	46.15904130943102
1993	41.564741887905605
1994	38.58298310066128
1995	37.632999308915
1996	32.85670372792675
1997	35.29458359821996
1998	36.362445161290324
1999	35.34191146881288
2000	35.4342159559835
2001	36.550786736020804
2002	39.85972293814433
2003	38.00172503242542
2004	38.840789306174415
2005	38.00512868801004
2006	38.04147148988351
2007	38.55974233128834
2008	35.51022426682001
2009	35.91440437862202
2010	35.46390259329538
2011	36.623375715193895
2012	36.59748187211601
2013	36.19278767123288
2014	31.435406226271827
2015	32.131495823842066
2016	27.640703517587937