It depends...
scaa71,
As is so often true of your posts, you did not include enough information to permit a complete answer. I will however supply a partial answer.
If the dealer is FORCED to complete her hand each round (and she stops at five cards), she'll get a 5-card unbusted hand on 1.9148% of the rounds for a 6D, S17 game. As you'd expect, this percentage will be lower for higher TC rounds: for example, for rounds begun at a HiLo TC of +4, she'll get a 5-card unbusted hand only 1.4463% of the time. Conversely, the percentage is higher at lower TC's: for example, at a HiLo TC of -4, she'll get a 5-card unbusted hand 2.4391% of the time.
On the other hand, if the dealer completes her hand only when necessary, then the answer depends on the number of spots in play as well as on the players' strategies. For a heads-up HiLo player, the corresponding percentages are 0.9498% overall, 0.1256% at +4, and 2.1007% at -4.
Hope this helps!
Dog Hand