You Handle These Passives

BB is 38/13/1.0
CO is 54/18/1.1
Button is 35/11/0.8

Party Poker 10/20 Hold'em (6 max, 6 handed) pokerhand.org hand converter

Preflop: Hero is SB with A[img]/images/graemlins/club.gif[/img], 5[img]/images/graemlins/club.gif[/img].
<font color="#666666">2 folds</font>, CO calls, Button calls, Hero completes, BB checks.

Flop: (4 SB) 8[img]/images/graemlins/spade.gif[/img], 6[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">Hero bets</font>, BB calls, CO calls, Button calls.

Turn: (4 BB) 9[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">Hero bets</font>, BB calls, CO calls, Button calls.

River: (8 BB) 3[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(4 players)</font>

How thin is a bet here?