Year % of total reserves 1970 132.53376935973478 1971 109.83655146811682 1972 91.07845595836088 1973 90.00980010756139 1974 104.43204714911722 1975 138.2339359888231 1976 245.54700705921562 1977 281.32340382897075 1978 217.95123012891383 1979 259.87353580269587 1980 387.1080690953612 1981 502.54857418857 1982 1474.3737534206023 1983 211.68285952519233 1984 80.41080396915532 1985 95.96962499132383 1986 88.40885043379731 1987 42.36054748609586 1988 124.53632052904081 1989 128.5117230343298 1990 157.40671112455664 1991 121.07754764186308 1992 127.97737501922298 1993 143.3172245995056 1994 610.4675656537131 1995 218.82767706899196 1996 152.80756331112758 1997 96.56155224118496 1998 82.60694119258851 1999 75.6000898510149 2000 53.21373782250998 2001 32.488579256394004 2002 47.18830621154598 2003 38.768895905164555 2004 31.637791590230623 2005 29.95694085608364 2006 34.40091404103306 2007 31.375498581762663 2008 25.370724086235384 2009 25.58328464856674 2010 35.710337277245635 2011 35.141188791216635 2012 45.44373971152132 2013 51.33819749105811 2014 41.64011270300857 2015 36.46070427648054 2016 26.402833433569572 2017 25.01538881576494 2018 31.824567910969538 2019 30.295124708815358 2020 23.29735015818756 2021 22.637666682310424 2022 27.22992080680342