Statistics Question

I think I know enough about statistics to be trusted with this, but I suspect some of you who do this day in and day out can check my method.

A particular state's murder rate per 100,000 for 1999 through 2010:

1999	6.6
2000	6.2
2001	6.6
2002	5.8
2003	5.1
2004	6.1
2005	6.9
2006	6.3
2007	6.2
2008	7.7
2009	6.5
2010	7.0

There was a change in state law for which the first full year was 2008.  The average for 1999-2007 was 6.2; for 2008-2010: 7.1 (rounded).  Std. dev. is 0.494 and 0.492, respectively.  Using Student's T (appropriate because n is so small for both year ranges), for a 95% confidence interval, .380 and 1.222 respectively.  This indicates that the 13.9% increase in murder rates for the years 2008-2010 is not statistically significant; the uncertainty range for 1999-2007 is 5.82 to 6.58; for 2008-2010, 5.84 to 12.91.  In short, it is impossible to determine at the 95% confidence level if the change in law caused the changed the increase in murder rate.  You have to get down to the 80% confidence level before you get statistical significance -- which isn't terribly impressive.

Interestingly: enough the firearms homicide rate, which may or may not include justifiable homicides, rose 25% -- far more than the murder rate.

Do I have this right?

UPDATE: I ran it by a nationally known economist who confirms that the methodology is right.