| Value | Category | Cases | |
|---|---|---|---|
| 1 | Are taken directly from establishment records | 108 | 
                                    
                                    17.6%
                                 | 
| 2 | Are estimates computed with some precision | 417 | 
                                    
                                    68.1%
                                 | 
| 3 | Are arbitrary and unreliable nuMGbers | 70 | 
                                    
                                    11.4%
                                 | 
| 4 | Are in some case taken from books and in some case estimates | 17 | 
                                    
                                    2.8%
                                 |