| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 | 
                                    
                                    7.4%
                                 | 
| 1 | One hour or less | 16 | 
                                    
                                    29.6%
                                 | 
| 2 | 4 | 
                                    
                                    7.4%
                                 | |
| 3 | 2 | 
                                    
                                    3.7%
                                 | |
| 4 | 5 | 
                                    
                                    9.3%
                                 | |
| 5 | 1 | 
                                    
                                    1.9%
                                 | |
| 6 | 2 | 
                                    
                                    3.7%
                                 | |
| 8 | 5 | 
                                    
                                    9.3%
                                 | |
| 12 | 2 | 
                                    
                                    3.7%
                                 | |
| 24 | 7 | 
                                    
                                    13%
                                 | |
| 36 | 1 | 
                                    
                                    1.9%
                                 | |
| 48 | 2 | 
                                    
                                    3.7%
                                 | |
| 64 | 1 | 
                                    
                                    1.9%
                                 | |
| 72 | 2 | 
                                    
                                    3.7%
                                 | |
| Sysmiss | 161 |