Year % of total reserves 1970 0 1971 0 1972 0 1973 0 1974 0.37034944659342117 1975 6.127596789185696 1976 14.45048390833449 1977 13.453141911836214 1978 2.7431599708860572 1979 12.545630406852249 1980 22.808613071895422 1981 53.39189620382366 1982 148.2076479211877 1983 106.6317358191875 1984 215.2829389805441 1985 259.78547386524195 1986 135.31834317101732 1987 520.9174134794217 1988 755.2630491699238 1989 2558.5258313794684 1990 2733.5290153988994 1991 2127.58485872221 1992 713.189179922302 1993 526.8111039154884 1994 39.712334235502404 1995 77.58784743888592 1996 91.2244847015901 1997 24.597764743045992 1998 68.4494710535222 1999 87.2966844880659 2000 94.08466318181696 2001 37.53448832596572 2002 12.255912738349442 2003 25.208518640561838 2004 17.186720968967332 2005 12.423313299401032 2006 6.50284474009523 2007 2.3378177705179053 2008 4.089074773805093 2009 5.679510058241162 2010 1.0066709831195795 2011 7.970287626131454 2012 46.23556053182044 2013 40.12859050373333 2014 35.56234220873387 2015 36.94748414082646 2016 40.41388391424749 2017 35.52040113879873 2018 37.60892925627509 2019 35.17952715972915 2020 25.99081345845498 2021 19.170895231606274 2022 25.881651308810937