Table:
text: 2007–08 Montreal Canadiens season
Eastern Conference Semi-finals: vs. (6)
Eastern Conference Semi-finals: vs. (6)
Date_ Venue Visitor Score Home Montreal_goals Decision Attendance Series
April 24 Bell Centre Philadelphia Flyers 3 – 4 Montreal A.Kostitsyn, Kovalev (2), Kostopoulos Price 21273 Montreal leads 1-0
April 26 Bell Centre Philadelphia Flyers 4 – 2 Montreal Koivu, Markov Price 21273 Series tied 1-1
April 28 Wachovia Center Montreal 2 – 3 Philadelphia Flyers Plekanec, Koivu Price 19849 Philadelphia leads 2-1
April 30 Wachovia Center Montreal 2 – 4 Philadelphia Flyers Plekanec, Koivu Halak 19872 Philadelphia leads 3-1
May 3 Bell Centre Philadelphia Flyers 6 – 4 Montreal Plekanec, Kovalev, Higgins, A.Kostitsyn Price 21273 Philadelphia wins 4-1

Question: What was the average attendance at the 2007-08 Eastern Conference semifinals: vs. Montreal Canadiens (6) season when decision was prize and Montreal were the visitors?