| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 | 
                                    
                                    7.4%
                                 | 
| 0 | Less than 1 hour | 19 | 
                                    
                                    27.9%
                                 | 
| 1 | 6 | 
                                    
                                    8.8%
                                 | |
| 2 | 6 | 
                                    
                                    8.8%
                                 | |
| 3 | 2 | 
                                    
                                    2.9%
                                 | |
| 4 | 4 | 
                                    
                                    5.9%
                                 | |
| 5 | 1 | 
                                    
                                    1.5%
                                 | |
| 8 | 3 | 
                                    
                                    4.4%
                                 | |
| 10 | 2 | 
                                    
                                    2.9%
                                 | |
| 12 | 2 | 
                                    
                                    2.9%
                                 | |
| 20 | 2 | 
                                    
                                    2.9%
                                 | |
| 21 | 1 | 
                                    
                                    1.5%
                                 | |
| 24 | 4 | 
                                    
                                    5.9%
                                 | |
| 34 | 1 | 
                                    
                                    1.5%
                                 | |
| 40 | 2 | 
                                    
                                    2.9%
                                 | |
| 48 | 4 | 
                                    
                                    5.9%
                                 | |
| 60 | 1 | 
                                    
                                    1.5%
                                 | |
| 72 | 2 | 
                                    
                                    2.9%
                                 | |
| 120 | 1 | 
                                    
                                    1.5%
                                 | |
| Sysmiss | 43 |