For any distribution, the first sextile, by definition, must be 100/6 = 16.66... %

–adjective 1. Astronomy. noting or pertaining to the aspect or position of two heavenly bodies when 60° distant from each other. –noun 2. Astronomy. a sextile position or aspect. 3. Astrology. a sextile position or aspect, conducive to mental stimulation. 4. Statistics. a quantile for the special case of six equal proportions. from dictionary.com

The cast of Sextile Aspect - 2014 includes: Michelle Beck as Hayden Jimmy Dailey as Party Goer Victoria Fragnito as Party Goer Kenneth Futch as Party Goer Laura Kiser as Party Goer Andy Lucien as Jesse Erica Trumpet as Party Goer

In astrology the month you were born has no relevance on how lucky a person is. To interpret luck in a chart I would look at Jupiter and if there are any sextile or trine aspects that Jupiter has with any of the other planets.

By definition, the 1st 6-tile is the point below which 1/6 of the population falls (irrespective of which distribution is involved). The 2nd 6-tile is the point below which 2/6 of the population falls.

This is 100 * 1/3 ~ 33.3% of the population.