Year	Percent
1950	30.57997
1955	29.61147
1960	28.08042
1965	25.72684
1970	23.66155
1975	23.15607
1980	24.00865
1985	26.93581
1990	29.63315
1995	32.38375
2000	34.6516
2005	36.21851
2010	38.0014
2015	36.36748
2020	33.43349
2025	30.06463
2030	27.78471
2035	29.15387
2040	31.12824
2045	32.51598
2050	31.83669
2055	29.27942
2060	27.72645
2065	27.37333
2070	27.76413
2075	28.06605
2080	27.69459
2085	26.70457
2090	25.53932
2095	24.75542
2100	24.54344