 The total Swiss population change in 2008 (from all sources, including moves across municipal borders) was a decrease of 4 and the non-Swiss population change was a decrease of 2 people.This represents a population growth rate of -0.9%.The age distribution, , in Sessa is; 60 children or 8.9% of the population are between 0 and 9 years old and 72 teenagers or 10.7% are between 10 and 19.