Year	% of internal resources
1975	31.03448275862069
1976	31.758620689655174
1977	32.48275862068966
1978	33.20689655172414
1979	33.93103448275862
1980	34.6551724137931
1981	35.310344827586206
1982	35.96551724137931
1983	36.62068965517241
1984	37.27586206896552
1985	37.93103448275862
1986	37.227586206896554
1987	36.52413793103448
1988	35.82068965517241
1989	35.11724137931034
1990	34.40206896551724
1991	36.23827586206897
1992	38.07448275862069
1993	38.0503448275862
1994	38.57448275862069
1995	38.815862068965515
1996	39.08993103448276
1997	40.179517241379315
1998	41.269103448275864
1999	42.35868965517241
2000	43.44827586206896
2001	47.26379310344828
2002	51.07931034482759
2003	49.25172413793103
2004	47.42413793103448
2005	45.59655172413793
2006	43.76896551724138
2007	41.94137931034483
2008	40.11379310344827
2009	38.286206896551725
2010	36.45862068965518
2011	36.45862068965518
2012	36.45862068965518
2013	36.45862068965518
2014	36.45862068965518
2015	36.45862068965518
2016	36.45862068965518
2017	36.45862068965518
2018	36.45862068965518
2019	36.45862068965518
2020	36.45862068965518