| Year | Value | | 2022 | 42.273337511442 | | 2021 | 38.024558166658 | | 2020 | 32.230173860198 | | 2019 | 36.198456482592 | | 2018 | 37.388295172377 | | 2017 | 36.248710846454 | | 2016 | 33.696262787832 | | 2015 | 35.628171507128 | | 2014 | 41.682144009416 | | 2013 | 43.160257175575 | | 2012 | 45.010075401777 | | 2011 | 44.481796166982 |
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