1                
            7 4               
       9           9          
      7 8         7 4         
 5           1           5    
7 3         7 8         2 4   
       9           9          
      7 3         2 8         
 5           1           5    
7 4         2 3         6 8   
       9           9          
      2 4         6 3         
 5           1           5    
2 8         6 4         6 3   
       9           9          
      6 8         6 4         
             1                
            6 8         


I believe that all other ways are rotations of this one. (But I haven't proved it.)