| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 | 
                                    
                                    2.2%
                                 | 
| 0 | Less than 1 hour | 16 | 
                                    
                                    35.6%
                                 | 
| 1 | 9 | 
                                    
                                    20%
                                 | |
| 2 | 4 | 
                                    
                                    8.9%
                                 | |
| 3 | 3 | 
                                    
                                    6.7%
                                 | |
| 4 | 4 | 
                                    
                                    8.9%
                                 | |
| 6 | 1 | 
                                    
                                    2.2%
                                 | |
| 7 | 2 | 
                                    
                                    4.4%
                                 | |
| 13 | 1 | 
                                    
                                    2.2%
                                 | |
| 24 | 1 | 
                                    
                                    2.2%
                                 | |
| 30 | 2 | 
                                    
                                    4.4%
                                 | |
| 48 | 1 | 
                                    
                                    2.2%
                                 | |
| Sysmiss | 105 |