Edited: Originally I had stated that Patrone was the lowest (5 traces and 0.119%), however the data shows that's incorrect. The correct hunter has been named below.
On 2018/2/11 I decided to gather some data from trace scrolls and slap it all into a spreadsheet. The spreadsheet is organized by individual hunter, their rank, their element, and their role. Data was calculated by taking the difference between initial traces and the traces after popping all the scrolls, then comparing the final individual amounts to the total amount of traces gained to get the percentage. Calculations took into account certain special event characters whose traces are not a part of the drop pool either because they were part of an event (i.e: Witch Riko, Santa Girl Reb., Wonderland Tyltyl), or because I do not have those characters (i.e: Vincent, Sunny). Percentages were calculated to three decimal points, as some of the 3* percentages are really similar.
Total scrolls spent: 1056
Total traces returned: 4208
Highest Individual Chance: Lapis (358 traces) 8.508%
Lowest (non zero) Individual Chance: Papillon (4 traces) 0.095%
3*: (277 traces) 6.583%
2*: (1079 traces) 25.642%
1*: (2852 traces) 67.776%
Fire: (1504 traces) 35.741%
Lightning: (1222 traces) 29.040%
Ice: (1482 traces) 35.219%
Attacker: (1346 traces) 31.987%
Defender: (991 traces) 23.550%
Bomber: (1066 traces) 25.333%
Healer: (805 traces) 19.130%
I did this because I thought it would be fun (it was!). I can supply the percentages (and scroll amounts) of the other individual characters in a separate post if anyone's interested. I'm planning on doing this again once I get 1000 trace scrolls again!