Accepted Penalty Yards per week, 2007 season

Time to get ready for the 2008 NFL Season.  Let's take a short look at the penalty yards accepted per week in the 2007 season.  I expected to see lots of penalty yards the first two weeks as the teams get out of pre-season form and then perhaps less penalties toward the end of the season in case players by then have figured out how the refs call the games.

But actually, the numbers show the biggest weeks for accepted penalty yards were in the middle of the season -- week 8 and week 9.  Although the lowest accepted penalty yards were close to the end of the season (weeks 14 and 15), the final week (week 17) did have a bunch of penalty yards.  Maybe just random statistical variation because it is such a small sample size.  Or maybe some influence of starters resting in the last week and using players with less practice/experience? 

1: 89.6
2: 96.3
3: 84.6
4: 87.1
5: 91.2
6: 91.4
7: 87.7
8: 106.8
9: 112.0
10: 97.4
11: 94.3
12: 79.2
13: 96.1
14: 76.3
15: 72.3
16: 81.1
17: 92.0