Level 19 is about the "middle" of the Aes Sedai strength range (at least for named characters) making roughly 50% of the Aes Sedai being strong enough to Travel.
108 Aes Sedai women above level 19
101 Aes Sedai women below level 19
15-16 years of training seems to be about the average time. 73 women completed training in 16 years or less, 87 women took longer.
Most women spend less time as Accepted than as Novice, in some cases a LOT less time, but most of the time it is no more than 1-2 years longer as a Novice. Team Jordan tended to explain when a woman spend a significant time as a Novice (typically lied about age or was some kind of discipline problem etc).
Weak women generally take longer in training time than strong women. 30 women managed to achieve the Shawl in 10 or fewer years only 4, Amico (27), Lyrelle Arienwin (24), Vandene (22) and Adeleas (23) had weaker than 19 strength.
Of the 73 women who achieved the shawl in fewer than 16 years 24 had less than 19 strength.
of the 87 remaining women with training times, 38 were below strength 19
Black Ajah seems to skew high in strength ... of the 34 Aes Sedai we know are Black and have a strength score, only 8 are weaker than level 19
Nationality breakout (every nation is represented):
52 Andorans (counting Two Rivers)
45 Seanchan
44 Aiel
24 Sea Folk
24 Taraboner
23 Domani
21 Arafellin
18 Tairen
17 Cairhienin
17 Saldaean
16 Murandian
14 Kandori
12 Illianer
9 Altaran
8 Ghealdanin
6 Far Madding (including a False Dragon)
6 Shienaran
5 Amadicians
3 Mayener
2 Black Hills
1 Malkieri (counting Nynaeve as Andoran)
1 Sharan
1 Tinker
Age Ranges
4 400-600+
11 300-400 (2 Aes Sedai lived past 300)
24 200-300
76 100-200
58 50-100
68 <50
Ajah
60 Green
53 Brown
48 Gray
45 Yellow
42 Red
39 Blue
37 White
42 Black
*please note that not all Aes Sedai had complete information on strength, training time or Ajah etc so the numbers here don't add up consistently.
This is further proof that natural skill increases with strength. This is very obvious with very strong channelers like Egwene and Elayne who could fully channel within only two years and with multiple flows. However, it is nice to see how the trend continues all the way down. Weaker women take longer to master channeling. Not a surprise at all.
It's also interesting that the BA are so strong. They might target stronger women for conversion, or kill the, if they refuse , or stronger channelers enjoy power and find other ways to become "more powerful".
While it's obvious that stronger women generally move through training faster, I'm not sure we can say that strength = faster to learn. We've seen many weak women learn weaves quickly, I think it's more about how long it takes them to gain strength. Aes Sedai won't let a woman advance to Accepted until she's hit roughly level 53 in strength. If women gain strength at a relatively steady pace once they begin channeling you have to figure that a stronger woman probably achieves these strength minimums a bit faster than a weaker woman (i.e. if a woman gains 5% of her strength a year a stronger woman would naturally hit the minimum levels before a weaker woman).
I think what we can also look to is the stronger women who did NOT move quickly:
Shemerim = behavior
Silviana = Issues learning despite her strength
Merise = spent 15 years as novice because she was so young, she was only 5 years as Accepted
I think this sort of tells us that most of the time strong women attain the necessary strength at a quicker pace, but that they don't always have the learning capacity or personality necessary to move quickly through training. Merise, because she was so young would have gained strength more slowly (we are told that the older a woman is when she begins training the faster she will gain her strength).