How long did a series of 6 erotic feature films run after being ushered in by the 1965 Danish coming-of-age sex comedy;Sytten?
Sytten:  Based upon the semi-autobiographical 1953 novel by Carl Erik Soya, Sytten was a financial success for the Palladium Film company and ushered in a wave of erotic films such as the "Bedside"-films and "Zodiac"-films, most of which starred Søltoft. Zodiac-films: The "Zodiac"-films is a series of six feature films from 1973–78, and form part of the wave of erotic films from Denmark.
from 1973–78