public bool hasDstInYear(int year)
        {
            foreach (Transition tr in Transitions)
            {
                if (GPTimestamp.Year(tr.Timestamp) == year)
                {
                    return(true);
                }
            }

            return(false);
        }
        public DateTime EndDateInYear(int year)
        {
            Transition selected = null;

            foreach (Transition tr in Transitions)
            {
                if (GPTimestamp.Year(tr.Timestamp) == year && tr.Dst == false)
                {
                    selected = tr;
                    break;
                }
            }
            if (selected == null)
            {
                return(new DateTime());
            }
            return((new GPTimestamp(selected.Timestamp)).getDateTime());
        }