Heavenly Stem & Earthly Branch
The weights of Five Elements are for balancing your Five Elements. To find your Five Elements is from Chinese Fortune Calendar. Your 40% luck is determined from here. Another 40% luck is determined by your decade cycles from Chinese Fortune Calendar, too. The rest of 20% luck is determined by something else.
The theory of Chinese Five Elements is the foundation of Chinese Horoscopes. The main menu of the Chinese Five Elements is a rich resources page to learn Chinese Astrology. You can make inquiries the scores, charts, relationships, and weights of Five Elements.