| N | Minimum | Maximun | Mean | Std. Dev. |
Number of cigarettes per day | 152 | 10 | 40 | 20 | 6.2 |
Age of smoking initiation | 152 | 15 | 24 | 17.7 | 1.5 |
Years of smoking | 151 | 26 | 60 | 43 | 8.2 |
Duration of smoking cessation (in months) | 17 | 5 | 192 | 55.4 | 44.1 |