Year	% of total
1991	54.31214908921977
1992	39.85826006323447
1993	39.8609681863638
1994	40.333388897599036
1995	40.28723788886482
1996	40.69537864196984
1997	39.098558863446854
1998	38.02592470692305
1999	38.13885810880142
2000	37.62713636538555
2001	36.8768685640061
2002	36.70084268856323
2003	36.5127551926207
2004	35.95472395871252
2005	35.70067511998166
2006	36.76855441758478
2007	35.918814802602
2008	36.098560659176556
2009	34.536307778956505
2010	34.818955045110336
2011	34.519121433319306
2012	36.40886170439022
2013	35.46884979316049
2014	34.77030400902401
2015	35.97150550973778
2016	35.82511954233579