| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 9 | 
                                                                 
                                    
                                    10%
                                 
                                                             | 
                                                        
                    
| 0 | Less than 1 hour | 30 | 
                                                                 
                                    
                                    33.3%
                                 
                                                             | 
                                                        
                    
| 1 | 11 | 
                                                                 
                                    
                                    12.2%
                                 
                                                             | 
                                                        
                    |
| 2 | 13 | 
                                                                 
                                    
                                    14.4%
                                 
                                                             | 
                                                        
                    |
| 3 | 3 | 
                                                                 
                                    
                                    3.3%
                                 
                                                             | 
                                                        
                    |
| 4 | 7 | 
                                                                 
                                    
                                    7.8%
                                 
                                                             | 
                                                        
                    |
| 5 | 3 | 
                                                                 
                                    
                                    3.3%
                                 
                                                             | 
                                                        
                    |
| 6 | 2 | 
                                                                 
                                    
                                    2.2%
                                 
                                                             | 
                                                        
                    |
| 10 | 3 | 
                                                                 
                                    
                                    3.3%
                                 
                                                             | 
                                                        
                    |
| 20 | 1 | 
                                                                 
                                    
                                    1.1%
                                 
                                                             | 
                                                        
                    |
| 24 | 4 | 
                                                                 
                                    
                                    4.4%
                                 
                                                             | 
                                                        
                    |
| 48 | 1 | 
                                                                 
                                    
                                    1.1%
                                 
                                                             | 
                                                        
                    |
| 72 | 2 | 
                                                                 
                                    
                                    2.2%
                                 
                                                             | 
                                                        
                    |
| 120 | 1 | 
                                                                 
                                    
                                    1.1%
                                 
                                                             | 
                                                        
                    |
| Sysmiss | 274 |