From the figures that are reported each game (usually given out on the official Albion twitter feed; typically reported in the Argus along with the match report; and sometimes given in the away side's match report on their official site).
Taking regular season League matches only, it is the ninth worst away support.
The worst 3:-
Wigan; 161; Nov 4 2014
Rotherham; 165; Sep 15 2015
Barnsley; 181; Dec 3 2013