|  
                Year  
            |  
         
             Beginning Price  
            |  
         
             Ending Price  
            |  
         
             Gain or Loss 
            |  
         
             Percent Gain or Loss  
            |  
      
|  
           2013 
            |  
         
           67.76 
            |  
         
           122.59 
            |  
         
           54.83 
            |  
         
           80.92% 
            |  
      
|  
           2014 
            |  
         
           122.59 
            |  
         
           75.44* 
            |  
         
           -47.15 
            |  
         
           -38.46% 
            |  
      
|  
           2015 
            |  
         
           37.72 
            |  
         
           45.11 
            |  
         
           7.39 
            |  
         
           19.59% 
            |  
      
|  
           2016 
            |  
         
           45.11 
            |  
         
           36.87 
            |  
         
           -8.24 
            |  
         
           -18.27% 
            |  
      
|  
           2017 
            |  
         
           36.87 
            |  
         
           39.02* 
            |  
         
           2.15 
            |  
         
           5.83% 
            |