Most of the increase has been because of the drug war, though as Mexico becomes more violent there has been a small rise in homicides not related to the drug war.
What stands out from the chart of the most violent municipalities for females is that Almoloya and Texcoco in the state of Mexico made the list (hint hint future gubernatorial candidates).
In this chart I show the maximum and minimum homicide rates from 1990 to 2006 (right before the drug war started) and compare it with the 2009 rate to put it in historical perspective:
The monthly totals:
Taking into account the undercount for the last year the totals would be:
2006 - 10,429
2007 - 8,843
2008 - 14,175
2009 ~ 19,900 (19,121 recorded in the database)
which assuming a population of 111 million (there were 112.3 million Mexicans in the 2010 census) would give a homicide rate of:
which is of course quite different from the 16,117 homicides according to police reports, and their corresponding rate of 15.
The mean age for homicide victims in 2009 was 34.6 with a sd of 14.3 years (it hasn't changed significantly since 2006):
homicides commited with a firearm slowed down:
P.S. The code is at my GitHub