| Value |
Category |
| 1 |
Less than 1 year |
| 2 |
1 to 4 years |
| 3 |
5 to 9 years |
| 4 |
10 or more years |
| 8 |
Unknown |
| 9 |
NIU (not in universe) |
Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.