An average of 6.1 goals per game have been scored during the 2017-18 season, up from 5.54 in 2016-17, which was right around the average for the past 10 seasons. The 6.1 mark is the highest average for goals per game since 2005-06, when it was 6.16, and the second-highest since a 6.28 average in 1995-96.
In 2005-06, the higher scoring rate was a result of an unusually high average of 11.7 power-play opportunities per game and a shooting percentage of 9.9. The same explanation applies in 1995-96, which averaged 10.1 power plays per game and a shooting percentage of 10.2.
This season's averages of 7.0 power plays per game and an 8.9 shooting percentage is slightly above the average for the previous 10 seasons, 6.94 and 8.56 percent, respectively. It's not quite enough to explain the entire gain.
The cause for the rise in goals is most likely due to an increase of shot volume, from an average of 60.2 shots per game in 2016-17, to 63.4 in 2017-18, which is the highest since 63.8 per game in 1970-71. The average for the past 10 seasons is 59.6 shots per game.