SMB.

For about 6 seasons the two most popular professional arena sports in North America are struggling to increase their average attendance.

Even though, during the 2007-08 season, the NBA averaged 17,396 fans per game (2% down from the previous year), and was still the third-highest average attendance in league history, compared to NHL´s 17,268 fans per game.

The biggest difference between the leagues may be this: 4 NHL teams play to less than 80% capacity, compared to 8 NBA teams. Four NBA teams (Charlotte, Philadelphia, Sacramento and Memphis) are currently averaging fewer fans per game than the team with the lowest attendance in NHL.

On the other site, NBA still has higher attendance than the NHL and even with a attendance declining in the past 2 seasons, last year´s average still ranked among the best in league history.
The chart below shows the despite all the buzz around this topic, NBA attendance is dropping and NHL´s is increasing . So the NHL is definitely gaining on the NBA in attendance, even if not as dramatically as has been portrayed.