Older, black women least likely to kill themselves

The Centers for Disease Control released today nine year’s worth of suicide statistics, gathered from 1999 to 2008, for people ages 45–64

Some findings:

• The suicide death rate for persons aged 45–64 years increased overall in the nine years, from 13.2 to 17.6 per 100,000 population
• Throughout the period, the suicide rate was highest for white men — 30.7 per 100,000 population.
• Second highest? Black men at 10.3 percent per 100,000 population.
• White women were next, 9.4 percent per 100,000 population.
• The rate for black women was dramatically lower than all other categories above. Only 1.6 per 100,000 population.

Any theories why suicide rates shake out this way?