| Value | Category | Cases | |
|---|---|---|---|
| 1 | Boiling | 3017 |
82.5%
|
| 2 | Filtering | 32 |
0.9%
|
| 3 | Add chemicals | 4 |
0.1%
|
| 4 | Boil and filter | 601 |
16.4%
|
| 5 | Other | 1 |
0%
|
| Sysmiss | 822 |