It is based on the statistics of the world birth rate. Let me tell you, I am Aries. I am very satisfied with the birth rate of the constellation. Average age (population). Libra 1 1.4% 7 1 Taurus1.2% 73 virgo 10.6% 76 Aries 9.3% 69 Scorpio 8.8% 77 Sagittarius 8.2% 77