| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 18 | 
                                    
                                    6.2%
                                 | 
| -4 | Too many to count | 160 | 
                                    
                                    55.4%
                                 | 
| 0 | 16 | 
                                    
                                    5.5%
                                 | |
| 1 | 7 | 
                                    
                                    2.4%
                                 | |
| 2 | 11 | 
                                    
                                    3.8%
                                 | |
| 3 | 11 | 
                                    
                                    3.8%
                                 | |
| 4 | 12 | 
                                    
                                    4.2%
                                 | |
| 5 | 10 | 
                                    
                                    3.5%
                                 | |
| 6 | 4 | 
                                    
                                    1.4%
                                 | |
| 7 | 6 | 
                                    
                                    2.1%
                                 | |
| 8 | 2 | 
                                    
                                    0.7%
                                 | |
| 9 | 1 | 
                                    
                                    0.3%
                                 | |
| 10 | 14 | 
                                    
                                    4.8%
                                 | |
| 12 | 4 | 
                                    
                                    1.4%
                                 | |
| 13 | 1 | 
                                    
                                    0.3%
                                 | |
| 15 | 2 | 
                                    
                                    0.7%
                                 | |
| 20 | 2 | 
                                    
                                    0.7%
                                 | |
| 25 | 1 | 
                                    
                                    0.3%
                                 | |
| 30 | 3 | 
                                    
                                    1%
                                 | |
| 31 | 1 | 
                                    
                                    0.3%
                                 | |
| 40 | 1 | 
                                    
                                    0.3%
                                 | |
| 50 | 1 | 
                                    
                                    0.3%
                                 | |
| 100 | 1 | 
                                    
                                    0.3%
                                 | |
| Sysmiss | 22 |