| Value | Category | Cases | |
|---|---|---|---|
| 1 | Spontaneous | 994 |
71%
|
| 2 | Induced | 161 |
11.5%
|
| 3 | Failed | 245 |
17.5%
|
| 8 | Unknown | 0 |
0%
|
| 9 | Missing | 0 |