As a flagship State Institution, you want your out of state population to be around 15% as stated earlier. However, out of state students are free money. So having more than less isn't a terrible thing. Our brain drain is as much a function of CT not being the most appealing place to a 22 year old grad with options. NYC and Boston will always be a draw. Chicago and the twin-cities do well in luring east coast kids to their cities. And of course the South is pulling kids from everywhere. CT needs improved nightlife and public schools in the cities to keep our young grads in-state.
Info is pretty widely available regarding out of state student population at flagship public universities. The numbers are all over the lot. Michigan is quite high at 36%. Some other numbers are surprising. Fla - 3%, FSU - 9%, Ga - 9%, Clem - 29%, Indiana - 29%, Bama - 35%, UNC - 18% (by law), UVA - 26%, Texas - 5%, Penn St - 29%, OSU - 12%, UConn - 23%.
One general rule seems to be that the smaller states (Del, VT, NH, etc.) have >50% out of state students while the bigger states have more in state students by percentage. UConn does want to attract out of state students and it has done a good job of it. Talk to any college advisor at a CT high school and they will tell you UConn is a tough nut to crack for in-state kids and getting more difficult all the time. It just has become a very good school at a relative bargain. In previous posts, I have mentioned that second tier private universities in the NE (i.e. Syracuse) are very concerned that schools like UConn, Rutgers and Maryland are cutting into their market because people don't see the value of spending 3X UConn's cost to send a kid to Syracuse. (I also see this as a reason the likes of Syracuse won't help us a bit with the ACC.)