Year % of total reserves 1970 68.74275395002957 1971 64.30464633370313 1972 57.21515267596043 1973 47.20651155005802 1974 27.704606343309262 1975 38.1745613857207 1976 39.80099869877413 1977 64.00849356460239 1978 67.0594201969182 1979 48.085776871025594 1980 52.99487974852546 1981 91.9256561884843 1982 105.76833021003324 1983 121.66320583368781 1984 148.99741681504395 1985 148.82334047180225 1986 110.73358956724871 1987 98.12813161043387 1988 111.18713777838809 1989 117.56500763287387 1990 116.63736511334072 1991 82.67881418179662 1992 68.90524218453488 1993 48.50349582908624 1994 39.95800264993742 1995 48.917824210210725 1996 47.4173215454607 1997 48.128668125723685 1998 41.0958280862965 1999 37.380840679195146 2000 31.22293477452873 2001 27.814894163548445 2002 23.50915160467607 2003 18.98368154092636 2004 17.095001940108858 2005 16.514667656540563 2006 17.64873559624123 2007 16.618883642825562 2008 18.26054317780254 2009 16.91040488080998 2010 20.64081927685817 2011 25.29523456874999 2012 29.453430866927405 2013 29.720145311633264 2014 27.401641987896344 2015 25.657668052769864 2016 25.793283907179656 2017 26.715675590186542 2018 26.877665881776576 2019 26.206261427031098 2020 22.2677130248737 2021 24.390411354387464 2022 32.01350062614963