Correlations | 2009 | 2010 | 2011 | 2012 | Mean |
2010 | 0.68*** |
|
|
|
|
2011 | 0.53*** | 0.47** |
|
|
|
2012 | 0.41** | 0.34* | 0.78*** |
|
|
Mean | 0.66*** | 0.67*** | 0.96*** | 0.82*** |
|
Variance | 0.41** | 0.37* | 0.96*** | 0.74*** | 0.89*** |