Year            Count     Valid     Min        Max        Mean       Stdev      Median
2007            1808      1738      18.307766  19.048866  18.665083  0.16603    18.650733 
2008            1808      1738      18.082834  18.948668  18.554431  0.209527   18.577333 
2009            1808      1738      17.856167  18.556934  18.244808  0.167019   18.262983 
2010            1808      1738      18.758499  19.566299  19.151856  0.163777   19.164967 
2011            1808      1738      17.780399  18.6807    18.232118  0.204537   18.23865  
2012            1808      1738      16.917833  17.757133  17.374297  0.198879   17.387816 
2013            1808      1738      18.100067  18.987766  18.570514  0.205962   18.588134 
2014            1808      1738      16.518467  18.188734  17.286135  0.35175    17.2931   
2015            1808      1738      19.300434  19.9006    19.597977  0.149511   19.611283 
2016            1808      1738      19.517866  20.055433  19.851054  0.118585   19.874217 
2017            1808      1738      18.291666  18.7367    18.576979  0.094656   18.596566 
2018            1808      1738      17.0602    18.155233  17.688682  0.258951   17.720133 
2019            1808      1738      15.6348    16.458433  16.073932  0.191161   16.093817 
2020            1808      1738      19.109533  19.834734  19.403972  0.126096   19.4071   
2021            1808      1738      17.253967  18.188366  17.766376  0.221715   17.782933 
2022            1808      1738      18.396896  19.089792  18.657527  0.141175   18.654396 
2023            1808      1738      18.071966  19.047667  18.665894  0.219331   18.694818