Each point on that plot represents a season worth of data. So how does the Premiership in 2013 compare to the Premiership in 2001?
Goals: 2012-13 was the fourth straight season that 1000+ goals have been scored, and the third straight in which 1050+. There are roughly 5% more goals now than in 2001, which translates to about 2.5 more goals per team over the course of a season.
Shots on target: Per game there were between 14-15 shots on target for the second straight season. After wavering a little between 2001 and 2006 they’re, up by a third in the past seven seasons, an increase of about 60 shots on target per team over a season.
Total shots: Decreased markedly this year, by ~3%. Whilst ~48% of shots were on target around 2000, there’s since been a steady increase, to the point where ~56% of shots are now on target.
Sh% & Sv%: The numbers for the ’00-01 and ’01-02 season look pretty anomalous. Maybe the definition of a shot on target was changed prior to the ’02-03 season? Since then there has been a steady drop in sh%. In ’12-13 the league average sh% was ~1.7% below the thirteen year mean, costing each team about 4-5 goals per season.
In short ’12-13 was another high scoring season, although the number of attacking events dipped somewhat.