| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 18 | 
                                    
                                    28.6%
                                 | 
| 1 | One hour or less | 8 | 
                                    
                                    12.7%
                                 | 
| 2 | 8 | 
                                    
                                    12.7%
                                 | |
| 3 | 8 | 
                                    
                                    12.7%
                                 | |
| 4 | 4 | 
                                    
                                    6.3%
                                 | |
| 5 | 3 | 
                                    
                                    4.8%
                                 | |
| 8 | 3 | 
                                    
                                    4.8%
                                 | |
| 10 | 1 | 
                                    
                                    1.6%
                                 | |
| 12 | 2 | 
                                    
                                    3.2%
                                 | |
| 16 | 2 | 
                                    
                                    3.2%
                                 | |
| 20 | 1 | 
                                    
                                    1.6%
                                 | |
| 23 | 1 | 
                                    
                                    1.6%
                                 | |
| 24 | 1 | 
                                    
                                    1.6%
                                 | |
| 30 | 1 | 
                                    
                                    1.6%
                                 | |
| 48 | 1 | 
                                    
                                    1.6%
                                 | |
| 300 | 1 | 
                                    
                                    1.6%
                                 | |
| Sysmiss | 48 |