| Value | Category | Cases | |
|---|---|---|---|
| 1 | Less than one year | 442 |
9.2%
|
| 2 | 1-5 years | 1787 |
37.2%
|
| 3 | 5-10 years | 941 |
19.6%
|
| 4 | 10-20 years | 1025 |
21.4%
|
| 5 | More than 20 years | 481 |
10%
|
| 6 | Don't know | 124 |
2.6%
|