Year	% of internal resources
1970	22.62859839546956
1971	24.898537045776305
1972	27.168475696083057
1973	29.438414346389806
1974	31.708352996696554
1975	33.9782916470033
1976	36.05474280320905
1977	38.131193959414816
1978	40.20764511562057
1979	42.284096271826336
1980	44.360547428032085
1981	45.16281264747522
1982	45.96507786691836
1983	46.76734308636149
1984	47.56960830580462
1985	48.37187352524776
1986	48.329400660689
1987	48.28692779613024
1988	48.2444549315715
1989	48.201982067012736
1990	48.15950920245399
1991	47.789837973808396
1992	47.42016674539877
1993	47.05049551675319
1994	42.4020764511562
1995	37.75365738555922
1996	33.57715903728173
1997	29.400660689004248
1998	30.10854176498348
1999	29.848985370457765
2000	22.770174610665407
2001	21.373289287399714
2002	21.760264275601696
2003	20.075507314771116
2004	16.809815950920242
2005	14.417177914110429
2006	12.576687116564417
2007	16.243511090136856
2008	17.0363378952336
2009	16.224634261444077
2010	14.67437470504955
2011	15.5545068428504
2012	15.294950448324682
2013	15.143935818782445
2014	14.82302973100519
2015	15.254837187352525
2016	15.040113260972154
2017	15.98159509202454
2018	15.13921661160925
2019	15.13921661160925
2020	15.13921661160925