12 mg/ml * 15 ml = 180 mg/day
180 mg/day * 365 days/year * 20 years = 1,324,000 mg/20 years
1,324,000 mg / 100mg/ml = 13,240 ml
13,240 ml / 1000 ml/L = 13 Liters (100 mg/ml)
I think that's right
But, you can also take into account that you can reduce your nicotine level as you go. I started...