Tale of the Tape - First Class Centuries

Ok time for a little Francis Payne.  Scoured BlackCaps.co.nz for information on Centuries scored in seasonal competition (State Championship and Plunket Shield) for the past 10 seasons and the following are the results:

2003/4 – 25
2004/5 – 34
2005/6 – 29
2006/7 – 53
2007/8 – 37
2008/9 – 62
2009/10 – 66
2010/11 – 36
2011/12 – 52
2012/13 – 36 at halfway stage.

So it's plainly obvious that after 2005/6 season something changed in either the conditions or the grounds (apart from the 2007/8 and 2010/11 seasons). Could it be the batsmen over this time actually got better (though this should translate to better BC performances??)

But it's looking like this season (if the weather plays ball) will be a record season for century makers