Year	% of total
1960	99.02015892157824
1961	99.04098583712091
1962	99.19266888828312
1963	99.30220699039042
1964	99.39761102012736
1965	99.10230936200503
1966	98.86613590207108
1967	98.77118596782275
1968	98.7821979763326
1969	98.63853600621097
1970	97.8669903112039
1971	98.0588816459674
1972	97.65361238772628
1973	97.62143893372101
1974	97.18269289767291
1975	96.22976002271247
1976	96.33004313491435
1977	95.20012737388139
1978	95.1884250975718
1979	94.83350375494135
1980	94.09208558741216
1981	92.97445558300925
1982	91.96987315651253
1983	91.65331347875984
1984	90.06462342232105
1985	87.92519035349943
1986	88.65357082848864
1987	87.90540583825604
1988	86.91009482983641
1989	86.4511843360393
1990	86.83788464222155
1991	87.09636476880391
1992	85.95284872182337
1993	86.00930916416696
1994	86.02180942313717
1995	85.81095470567577
1996	85.90869753410128
1997	84.62946066242358
1998	84.92246199140767
1999	83.93137164289224
2000	83.62197513548057
2001	83.60503301880446
2002	83.27815679295443
2003	83.18231408790263
2004	82.56602161666581
2005	81.85567626825777
2006	81.2718831767448
2007	81.27195015647062
2008	80.80225178337086
2009	79.96746885381566
2010	79.56035025958603
2011	80.3702087567313
2012	80.62522297866155
2013	81.08826801353561
2014	79.71052693699183
2015	78.86255105675498