Year	% of internal resources
1980	18.36763662171753
1981	18.181334279630946
1982	17.995031937544358
1983	17.808729595457773
1984	17.622427253371185
1985	17.4361249112846
1986	17.249822569198013
1987	17.06352022711143
1988	16.87721788502484
1989	16.690915542938257
1990	16.50461320085167
1991	16.534776437189496
1992	16.564939673527324
1993	16.595102909865155
1994	16.62526614620298
1995	16.65542938254081
1996	16.685592618878637
1997	16.715755855216464
1998	16.745919091554292
1999	16.776082327892123
2000	16.802696948190206
2001	16.841731724627394
2002	16.87721788502484
2003	16.912704045422284
2004	16.94819020581973
2005	16.983676366217175
2006	16.559261887863734
2007	16.134847409510293
2008	15.71043293115685
2009	15.286018452803408
2010	14.858055358410219
2011	15.04326552004613
2012	15.2249270656423
2013	15.406588611238467
2014	15.588250156834635
2015	15.769911702430802
2016	15.769911702430802
2017	15.769911702430802
2018	15.769911702430802
2019	15.769911702430802
2020	15.769911702430802