Year	% of internal resources
1974	13.086150490730644
1975	13.086150490730644
1976	13.58536289712832
1977	14.084575307161035
1978	14.583787713558708
1979	15.083000119956381
1980	15.582212529989095
1981	16.08142493638677
1982	16.580637342784442
1983	17.079849752817157
1984	17.579062159214832
1985	18.078274565612507
1986	18.577486975645222
1987	19.076699382042897
1988	19.575911788440568
1989	20.075124198473286
1990	20.574336604870954
1991	20.930570701563067
1992	21.286804798255183
1993	21.643038894947296
1994	21.999272991639405
1995	22.355507088331517
1996	22.31915667030171
1997	22.282806252271904
1998	22.24645583424209
1999	22.210105416212286
2000	22.173754998182478
2001	23.567187688113414
2002	24.96062038167939
2003	26.354053071610323
2004	25.7360959651036
2005	25.118138858596872
2006	24.790985096328612
2007	22.90076335877863
2008	27.84442021083243
2009	22.973464194838243
2010	23.15521628498728
2011	20.75608869501999
2012	21.155943293347875
2013	22.101054162122864
2014	22.537259178480554
2015	22.24645583424209
2016	22.537259178480554
2017	22.173754998182478
2018	21.483097055616142
2019	21.62849872773537
2020	22.064703744093055