| Year | Value | | 2024 | 9.3667592571186 | | 2023 | 15.175011140579 | | 2022 | 7.8225774417287 | | 2021 | 9.1885786113975 | | 2020 | 11.337488703404 | | 2019 | 20.53967117988 | | 2018 | 17.49883540449 | | 2017 | 16.837553328166 | | 2016 | 20.935692246031 | | 2015 | 25.513860923123 | | 2014 | 24.324623594338 | | 2013 | 26.156657676006 |
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