Write a question about the following article: On April 18, 2008, the club announced its final attendance figures for 2007–08. The club had 40 sell-outs out of 41 home dates, a total attendance of 812,665 during the regular season, placing the club third in attendance in the NHL. The number of sell-outs and the total attendance were both club records. The previous attendance records were set during the 2005–06 with a season total of 798,453 and 33 sell-outs. In 2006–07 regular season attendance was 794,271, with 31 sell-outs out of 41 home dates or an average attendance of 19,372.  In the 2007 playoffs, the Senators played 9 games with 9 sell-outs and an attendance of 181,272 for an average of 20,141, the highest in team history. The club has been regularly represented in the top half in attendance in the NHL.

Question about the article:
How many home dates did the club not sell out?