Year % of total reserves 1972 0 1973 0.37053031376833073 1974 0.033294428364688856 1975 1.3656914511739313 1976 1.1120037675104002 1977 11.199069974814954 1978 22.53644856556185 1979 26.870782847038704 1980 64.02559224274688 1981 142.81068762068963 1982 100.24680645087885 1983 31.150544377759363 1984 32.601101646817845 1985 37.915215799030406 1986 28.758869633060957 1987 8.448872261985 1988 4.625517659163536 1989 12.691688751728517 1990 23.641990385601886 1991 16.711153692893493 1992 12.554382969101214 1993 6.247026634759569 1994 6.127523041098611 1995 8.383142326737342 1996 8.722505648000137 1997 10.864323100244336 1998 7.734384873823906 1999 15.558843737026184 2000 22.03473410274505 2001 27.629788817434115 2002 33.22776555180004 2003 23.508131797181107 2004 22.09972440955844 2005 24.369094115563474 2006 30.383037097105465 2007 25.95311078461077 2008 32.71849522882448 2009 18.694709361594157 2010 26.374871291909297 2011 22.925271348866456 2012 15.345235788147034 2013 20.637130024808283 2014 18.597935771994013 2015 24.118147145089797 2016 24.26792895324042 2017 32.20000750310383 2018 28.191875306282117 2019 29.78056096210393 2020 25.448261262941397 2021 39.18117053407101 2022 54.90846278400371