Year % of total reserves 1970 32.884153226397046 1972 42.32277127045465 1973 41.24016445998692 1976 88.7706628569924 1977 124.29442306716471 1978 151.38517497543077 1979 118.05736230370816 1980 154.01386954947787 1981 182.03203222489205 1982 214.63534590126386 1983 205.16469749904888 1984 246.23198435708355 1985 288.7428055956562 1986 164.83934267608961 1987 207.30400357021642 1988 232.29358663586066 1989 278.15990807661524 1990 263.82235603453205 1991 206.07326785747333 1992 186.9904059013895 1993 174.9620071793201 1994 150.70054964151183 1995 142.4300352212386 1996 129.65259837092805 1997 120.50060897937098 1998 123.5358701792269 1999 117.60482559440814 2000 103.8608857993424 2001 88.72768697367827 2002 65.26450346434387 2003 55.68423310337484 2004 51.59009383043561 2006 44.656186347697364 2007 43.06568620874115 2008 34.349261119888006 2009 28.095263270965887 2010 25.627365962514652 2011 29.405073445602497 2012 30.727602927661177 2013 32.0024673830404 2014 31.592078392923042 2015 33.557001538856596 2016 33.56007177964338 2017 33.71834160664423 2018 29.057620144176717 2019 29.982473826720092 2020 26.806466203964852 2021 34.92672902118183 2022 37.238570361963355