Year | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 |
| 3.3 | 3.0 | 3.0 | 2.9 | 3.3 | 2.5 | 2.6 | 2.7 | 2.8 | 3.0 |
| 9.4 | 9.6 | 10.5 | 11.1 | 13.6 | 11.9 | 12.5 | 13.7 | 14.7 | 15.8 |
| 5430 | 6430 | 7684 | 8416 | 11,179 | 9838 | 10,682 | 11,739 | 18,110 | 13,725 |
| 23 | 8 | 44 | 30 | 16 | 15 | 17 | 17 | 14 | 14 |
| 2.12 ± 0.03 | 2.13 ± 0.01 | 2.08 ± 0.03 | 2.07 ± 0.03 | 2.20 ± 0.02 | 2.10 ± 0.01 | 2.10 ± 0.02 | 2.11 ± 0.01 | 2.10 ± 0.01 | 2.14 ± 0.01 |
| 0.67 | 0.04 | 0.60 | 0.93 | 0 | 0 | 0 | 0 | 0 | 0 |