| Value | Category | 
|---|---|
| 1 | do not smoke tobacco | 
| 2 | started smoking tobacco | 
| 3 | increased smoking of tobacco (have smoked longer than 2 months) | 
| 4 | decreased smoking of tobacco (have smoked longer than 2 months) | 
| 5 | quit smoking of tobacco (have smoked longer than 2 months) |