For how long has Esther Gokhale's book about the Gokhale Method been widely advertised and distributed?

The postural methods and related techniques that we teach and that franchisees teach, and the products that we and franchisees sell are intended primarily for restoring the body's primal architecture and movement patterns. The methods, techniques and products offered by a Franchised Business are not generally known to the public. Courses in techniques and methods aiming to address the same issues are available in various locations throughout the world. Esther Gokhale has extensively researched postural methods and programs for teaching posture over the last 30 years. She has taught the Gokhale Method throughout the United States and in various parts of the world; the Gokhale Method is the subject of her book, 8 Steps to a Pain-Free Back, which has been widely advertised and distributed in the last fifteen years; she has also shown the Gokhale Method through national television and DVDs of these programs are being sold. There have been no claims that the Gokhale Method infringes any other technique, program or method, and we have no reason to believe that such claims would or could be made. The market for our services is not seasonal.

Source: Item 1 — THE FRANCHISOR AND ANY PARENTS, PREDECESSORS, AND AFFILIATES (FDD pages 8–10)