Year	% of total
1971	51.68087140674752
1972	50.54122311754375
1973	53.30670814127022
1974	51.80670577508245
1975	53.26002674686453
1976	53.84164744245974
1977	54.95004947679586
1978	54.406999580515745
1979	53.40927283009277
1980	48.649336541046125
1981	44.80969065439432
1982	42.652028436691936
1983	43.80955951333785
1984	34.60136501058526
1985	35.1815827562893
1986	35.541824777403406
1987	39.427244009892654
1988	40.952822017642895
1989	41.92494620673347
1990	43.07913245665559
1991	44.280306312422994
1992	48.229530626529055
1993	49.273122648514004
1994	51.77030532910478
1995	55.37105065518333
1996	56.33445816964922
1997	57.72249014704703
1998	55.924924079688346
1999	53.21612679819331
2000	53.06860729621048
2001	54.30490274689199
2002	55.87291963199299
2003	57.21562392647206
2004	56.38303464461239
2005	57.8125893578486
2006	56.18237608083801
2007	57.274835454792594
2008	57.62975477132473
2009	56.26292370680965
2010	60.111169762133635
2011	59.880986221657416
2012	59.48380293563794
2013	61.41213905119647
2014	62.43489629218685