How to split capital gains distribution between two state returns since we moved mid-year? My 1099-DIV doesn't give the date that the capital gains distribution was made.

Since I'm not sure what date the distribution was made, I'm not sure if I split it in half and put half on our NY return and half on our IA return? We moved to IA from NY on 7/28/2015.

My question would also apply to how we handle the interest income from banks. Thanks!