99 on very drawy board

[I R BABOON]

BTN = 69/21/1.26
CO is unknown 3rd hand he'll play

CO ($1.52)
Button ($1.80)
SB ($1.78)
BB ($1.61) (Hero)

Preflop: Hero is BB with 9[img]/images/graemlins/heart.gif[/img], 9[img]/images/graemlins/club.gif[/img]
CO calls, Button calls, SB calls, Hero checks,

I failed to raise pre-flop, but now my thoughts are get to showdown as cheap as possible as to many draws are possible. Even if I hit a T or 5 at best I split it.

Flop: 6[img]/images/graemlins/spade.gif[/img], 8[img]/images/graemlins/club.gif[/img], 7[img]/images/graemlins/club.gif[/img] ( 2BB )
SB checks, Hero checks, <font color="#CC3333">CO bets</font>, Button calls, <font color="#666666">1 folds</font>, Hero calls,

Turn: 2[img]/images/graemlins/spade.gif[/img] ( 3.5BB )
Hero checks, <font color="#CC3333">CO bets</font>, Button calls, Hero calls,

River: 4[img]/images/graemlins/spade.gif[/img] ( 6.5BB )
Hero checks, <font color="#CC3333">CO bets</font>, <font color="#666666">1 folds</font>, Hero calls,

Final Pot: 8.1BB

How's this line?