Year	% of internal resources
1980	20.511627906976745
1981	20.576666666674416
1982	20.64170542634884
1983	20.70674418604651
1984	20.771782945744185
1985	20.836821705418608
1986	20.90186046511628
1987	20.966899224813954
1988	21.031937984488373
1989	21.096976744186048
1990	21.16201550388372
1991	21.20891472867442
1992	21.255813953488374
1993	21.06046511627907
1994	20.865116279069767
1995	20.66046511627907
1996	20.701162790697676
1997	20.74186046511628
1998	20.835658914720927
1999	20.929457364348835
2000	21.02325581395349
2001	20.33139534883721
2002	19.63953488372093
2003	19.56046511627907
2004	19.481395348837207
2005	19.40232558139535
2006	19.323255813953487
2007	19.244186046511626
2008	19.06651162790698
2009	18.888837209302327
2010	18.838272425255813
2011	18.787707641186042
2012	18.737142857139535
2013	18.68657807309302
2014	18.636013289046513
2015	18.585448504976743
2016	18.534883720930235
2017	18.441860465116278
2018	18.3953488372093
2019	18.232558139534884
2020	18.232558139534884