| Year | Value | | 2021 | 0.53524366868357 | | 2020 | 0.68208827446582 | | 2019 | 0.97223838950072 | | 2018 | 0.058638862697255 | | 2017 | 0.065621398193494 | | 2016 | 0.042056449990256 | | 2015 | 0.055841069134412 | | 2014 | 0.3463012333704 | | 2013 | 0.36109164480641 | | 2012 | 0.35430930265957 | | 2011 | 0.31235781072805 | | 1999 | 1.1224470054107 | | 1998 | 1.0758723921789 | | 1997 | 0.99233634397308 |
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