A new study tracking the marital status of more than 460,000 U.S. service members between 1999 and 2008 found that the likelihood of divorce increased with each passing month that a spouse was away at war. The research was done by the RAND Corp. and published in Journal of Population Economics. Sebastian Negrusa, an economist who co-authored the study says in a USA Today article, "Couples form expectations at the time of marriage. The length, conditions and risks of the deployment are sources of shocks to the value of military marriages." He goes on to add, "Couples who married before 9/11 just didn't expect that deployments were going to be amped up." From 2001 to 2011 the overall divorce rate in the military increased from 2.6% of marriages to 3.7%, according to Pentagon data. The USA Today article notes that the rate dipped slightly last year.