| 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 |
|---|---|---|---|---|---|---|---|---|---|
| 4·3% | 0·6% | 2·3% | 5·3% | 4·1% | 4·3% | 4·4% | 3·0% | 2·4% | 1·5% |
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