In terms of the Microcensus of the Federal Statistical Office:
Regular smoking is to be understood as daily smoking, even if only small amounts of tobacco are involved. A heavy smoker is according to the recommendations of the Word Health Organization (WHO) a smoker with a daily cigarettes consumption of more than 20 pieces. The age at start of smoking is the age, in which regular smoking begun for the first time. The number of daily smoked cigarettes was asked in the classes under 5, 5 to 20, 21 to 40 and 41 and more. From these results also the daily average number of smoked cigarettes was estimated. Because of the lack of specifics when determining these values it was assumed, that the exact number of smoked cigarettes was equally distributed within the bounds of the specified classes and that the open top class was closed at a value of 60. In the question "What do you smoke or what did you smoke mostly" the interviewees had to declare the prevalent type, if several tobacco types were smoked. As former smokers only those persons are reported, who do no longer smoke nowadays.
The Federal Health Monitoring System 23 Sep 2020