| Value | Category | Cases | |
|---|---|---|---|
| 1 | Are taken directly from establishment records | 164 | 
                                    
                                    25.4%
                                 | 
| 2 | Are estimates computed with some precision | 328 | 
                                    
                                    50.9%
                                 | 
| 3 | Are arbitrary and unreliable numbers | 23 | 
                                    
                                    3.6%
                                 | 
| 4 | Are in some case taken from books and in some case estimates | 130 | 
                                    
                                    20.2%
                                 |