Source: http://jennsenfire.free.fr/Cours%20Fac/L1S2/D%C3%A9mographie/Natalit%C3%A9,%20f%C3%A9condit%C3%A9/%C3%A2ge%20modal,%20%C3%A2ge%20m%C3%A9dian%20et%20%C3%A2ge%20moyen%20-%20%C3%A2ge%20modal,%20moyen%20et%20m%C3%A9dian.pdf