It looks like the lockout rules increased scoring slightly when they were implemented in 2006, but they've been declining ever since.  I think it may just part of a cycle though.  If you look at the early-to-mid 1990s trends, the scoring was up and down year by year.  I say give it another year or so and you might see a bit of a jump in the scoring again.  We shall see.

I think how the game was called / officiated and the goalie equipment also played a role in the decline. Along with "all of the above." I'd like to see how the graph for penalties called over the years matches up to scoring. That is very interesting stuff HolyRollin. Good job.

 You're right. I completely forgot to put the penalty/goalie pad reason up there. Thanks!

I really like your bell-curve. Nobody ever brings up the statistical anomaly aspect. I gotta find a site with this info. It's gotta be on hockey-reference or something.

Overall scoring has been up since the lockout. I think it has just become harder for a single skater to dominate. I am not sure why this is happening, though. It just seems like teams have become more relaint on three, or even four lines, instead of the old days where the top two lines would see most of the minutes, and third and fourth would just see PK time or "goon" time. There is also less 4 on 4 or even 3 on 3 time that was seen so often in the Gretzky days that would allow players like him to dominate. Increased penalties also keep star players off the ice when their team is the one taking the penalties.

I think there could be something to that.  Today's goons are relied upon to be a little more than just enforcers.  Many now actually have some hockey skills.  I think the days of the one-dimensional goon are almost over.