Year	% of total reserves
1980	91.70826656642339
1981	97.54642874174469
1982	64.82265271806294
1983	31.266262940171647
1984	30.43712500296577
1985	37.51331619096835
1986	33.326148071696984
1987	35.396672047546694
1988	50.92788345091388
1989	32.52050670193958
1990	66.22739165447261
1991	50.166473836046954
1992	32.736388363912326
1993	46.42646034169508
1994	31.238248602409662
1995	49.65042643718141
1996	36.14029560395724
1997	19.620121292544038
1998	15.177894741567902
1999	15.450534947475827
2000	22.453529084125698
2001	20.41076352220262
2002	17.893984458881715
2003	26.52445957950123
2004	27.196023826885984
2005	34.31537997030383
2006	54.845065142685954
2007	73.3619438948819
2008	64.29480337971962
2009	36.01116772083967
2010	35.707993211787205
2011	40.583959426392624
2012	34.94403590110469
2013	31.834555315143525
2014	28.43993498948489
2015	32.133218544637714
2016	30.873326959344986
2017	33.644397337618734
2018	38.62039687085864
2019	39.022804034082384
2020	34.042371722697354