| Value |
Category |
| 0 |
None |
| 1 |
1 to 14 hours (except tt1980, tt1990 and tt2000) |
| 2 |
15 to 29 hours (except de1970, ps2017, tt1980, tt1990, tt2000, and ve1971) |
| 3 |
30 to 39 hours (except de1970, ps2017, tt1980, tt1990, tt2000, and ve1971) |
| 4 |
40-48 hours (except il1972, tt1980, tt1990, and tt2000) |
| 5 |
49 hours or more (except il1972 and tt2000) |
| 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.