18a. About how long has it been since you last smoked cigarettes every day?
Number ____
1[] Days (19)
2[] Weeks (19)
3[] Months (if 1 year or 12 months ago go to 18b, otherwise go to 19)
4[] Years (if 1 year or 12 months ago go to 18b, otherwise go to 19)
999[] DK