Year % of total reserves 1970 290.50994726327565 1971 329.44676044222996 1972 225.89271800193234 1973 151.512314301968 1974 176.28729129373346 1975 159.97789545239752 1976 82.24713622368 1977 96.61638965025088 1978 68.5856070681057 1979 39.999458935987725 1980 36.099555416948135 1981 45.63627254982924 1982 55.73206228450811 1983 92.82459142851101 1984 160.625994299367 1985 141.26566715032467 1986 45.87610529621028 1987 48.471359674177826 1988 43.52665119570047 1989 41.86348276977665 1990 29.544273325197633 1991 25.607832924078917 1992 32.25965399275976 1993 45.38170819855393 1994 55.43261831537607 1995 65.60496845902985 1996 59.20441672399915 1997 58.13339361409396 1998 71.19542919844913 1999 48.93337315866505 2000 31.878695178763532 2001 32.086819503193034 2002 33.74070662951841 2003 32.56343621487821 2004 37.819492877485246 2005 37.69335181837842 2006 30.851014909867597 2007 24.631544487103614 2008 23.797092597957867 2009 16.058879959149902 2010 28.181436108720437 2011 33.22123299248565 2012 27.931372063008062 2013 25.234186579355868 2014 26.108644166158918 2015 25.82025291888515 2016 24.429840347293414 2017 27.64355953463339 2018 31.151074018647197 2019 29.695390345053585 2020 23.760247929532458 2021 27.33335912187642 2022 33.71727133491946