| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 | 
                                    
                                    5.7%
                                 | 
| 0 | Less than 1 hour | 7 | 
                                    
                                    20%
                                 | 
| 1 | 3 | 
                                    
                                    8.6%
                                 | |
| 2 | 9 | 
                                    
                                    25.7%
                                 | |
| 3 | 9 | 
                                    
                                    25.7%
                                 | |
| 4 | 3 | 
                                    
                                    8.6%
                                 | |
| 5 | 2 | 
                                    
                                    5.7%
                                 | |
| Sysmiss | 329 |