Year	% of internal resources
1980	15.773756621280526
1981	16.0717586832095
1982	16.369760745138468
1983	16.66776280706744
1984	16.96576486899641
1985	17.10192328202211
1986	17.236588574069465
1987	17.37125386611682
1988	17.505919158164172
1989	17.640584450211524
1990	17.77524974225888
1991	18.07624397122898
1992	18.377238200195524
1993	18.67823242916563
1994	18.807737820146468
1995	18.93724321112375
1996	19.06674860210459
1997	19.19625399308187
1998	19.32575938406271
1999	19.455264775039993
2000	19.58477016602083
2001	19.60752248569092
2002	19.63027480536101
2003	19.65302712503111
2004	19.6757794447012
2005	19.698531764371292
2006	20.192683707206086
2007	20.21756905684525
2008	20.480642753030683
2009	20.733051299370757
2010	20.862099612499556
2011	21.152547193288065
2012	21.28763909132923
2013	21.429841089267303
2014	21.095666394112836
2015	21.038785594937607
2016	21.473212698638413
2017	21.19591880265918
2018	21.078246649365422
2019	21.405666749617833
2020	20.209747946958657