Villain is 56/13, but only over 16 hands. No reads otherwise.

Full Tilt No-Limit Hold'em, $0.50 BB (9 handed) - Full-Tilt Converter Tool from FlopTurnRiver.com

saw flop | saw showdown

MP3 ($9.65)
CO ($17.65)
Button ($9.70)
SB ($41.05)
BB ($74.50)
UTG ($10.95)
Hero (UTG+1) ($50.10)
MP1 ($17.35)
MP2 ($10)

Preflop: Hero is UTG+1 with 9, 9
1 fold, Hero calls $0.50, 3 folds, CO bets $2, 3 folds, Hero calls $1.50

Flop: ($4.75) 5, 7, 2 (2 players)
Hero bets $4.50, CO raises to $15.65 (All-In), Hero calls $11.15

Turn: ($36.05) 5 (2 players, 1 all-in)

River: ($36.05) 3 (2 players, 1 all-in)

Total pot: $36.05 | Rake: $1.80

Results below:
Hero had 9, 9 (two pair, nines and fives).
CO had A, A (two pair, Aces and fives).
Outcome: CO won $34.25

I should fold at what point in this hand?