Year % of total reserves 1977 73.50215039008242 1978 86.27910585396602 1979 69.02831100765077 1980 57.636109966030055 1981 76.5535243511175 1982 59.89454218014581 1983 27.835663752700462 1984 36.09628388386007 1985 25.275146962433897 1986 36.11631836377009 1987 52.040161675310955 1988 68.97320046254933 1989 46.39462822194169 1990 35.79155433923232 1991 23.591908964445473 1992 18.40477137425295 1993 15.546777178063637 1994 23.006136342799078 1995 56.19701552438671 1996 54.000885563200605 1997 56.12549682297634 1998 48.58795044284748 1999 53.82963875720752 2000 86.51815355786859 2001 110.65045854929232 2002 71.25214703857846 2003 81.55244169652389 2004 91.9329982339179 2005 100.2459414353372 2006 65.40733657166545 2007 56.105485288041756 2008 58.32543858830254 2009 27.66013086505946 2010 29.004413277384433 2011 49.04287844285898 2012 48.05570794900015 2013 67.50703327753381 2014 74.92669148692443 2015 72.403755590775 2016 78.21709333151531 2017 57.28063722770952 2018 58.01599561420952 2019 50.213338845372824 2020 60.69721863031842 2021 65.90588297861292