Year	% of total
1971	86.08463591307664
1972	82.38341968911918
1973	90.24924678170365
1974	85.79141104294479
1975	72.75080906148868
1976	70.22385179467388
1977	67.13951935914552
1978	66.1893169125018
1979	67.88532961931291
1980	56.14540618419595
1981	52.46130803794309
1982	32.019830754765366
1983	32.65861268901512
1984	31.905858644019002
1985	27.229681520399556
1986	33.87658695010334
1987	34.048198098607116
1988	31.09852543497117
1989	35.09129713066161
1990	44.56892352654652
1991	9.879406307977737
1992	37.91530944625407
1993	62.335216572504706
1994	55.05657398473818
1995	53.49856685213285
1996	62.45731108930323
1997	58.999401287232445
1998	41.832310565635005
1999	32.33151760831011
2000	32.939393001887204
2001	30.709350126825857
2002	21.989989549529728
2003	24.61936586101201
2004	27.697789412449097
2005	25.092605295650984
2006	31.409246539374465
2007	31.895473099091337
2008	35.67025449767146
2009	28.83907095610343
2010	34.629749776429534
2011	38.01799606662374
2012	36.222169020828346
2013	39.12629956380571
2014	33.748848633712
2015	36.4189169292382