xs Rattata (youngster medal)

I almost there : 271/300 for 2142 catches (12,65%)

108 / 996 = 10.8%

322 / 2751 11.7%

2751 / 3413 80.6% - If I'm short of balls I'll often 'run' if they're high cp.

XS / Caught: 174 / 1537 (11.3%)

Rattata seen: 1888
Rattata caught: 1537
Catch rate: 81.4%

Catch rate is a bit misleading because I often run on purpose if I'm low on balls or a Rattata seems especially hard to catch.

Total seen: 73
Total caught: 57
Catch rate: 78.1%
XS caught: 12

xs / caught: 64 / 484 (13.2%)

Rattata seen: 549
Rattata caught: 484
Catch rate: 88.2%

Ratio of rats of all caught pokemons:
484 / 21176 = 2.3%
(I think I live in a town with relative few rats)

106 / 875 xs (12.1%)
875 caught / 1057 seen = 82.7%

xs / caught: 24 / 193 (12.4%)

Rattata seen: 228
Rattata caught: 193
Catch rate: 84.64%

Same as others said, many times i run due to low balls.
I am currently level 30, but my figures are too low compared to yours.
Maybe ratatas are not that frequent here?

2915 seen
2520 caught
305 tiny rats.. Just hit last week!!
86% catch
12% tiny

16400 pokes
15% rats.... Woof.

XS / Caught: 516 / 4323 (11.9%)

Rattata seen: 5256
Rattata caught: 4323
Catch rate: 82.2%

Mons caught: 25622
16.9% Rats

2081 caught
235 xs rats
11.3 ish %

I have a very bad xs rate :(

xs / caught: 35 / 413 (8.4%)

Rattata seen: 517
Rattata caught: 413

Lvl 29 by the way, (I dont like grinding with rats).

xs / caught: 119 / 1128 (10.55%)

Rattata seen: 1326
Rattata caught: 1128
Catch rate: 85.07% (occasionally walking away from some)

Rats vs all caught pokemons (which I calculate as captures minus evolves): 1128 of 8746 = 12.90%

Lv 33 player here living in a town with not many rattata, I caught way more eevees instead：caught/seen: 369/420, catch rate: 87.9%,
xs: 40, XS rate: 9.524%