Don't know how relevant this is because it's from 2003:
The U.S. Census tracks stuff like this, but it takes some digging to get the numbers you want. Here's a 2003 article (
Honolulu Star-Bulletin Hawaii News) from the Star-Bulletin that might be a good place to start. The bureau counted 76,133 more people moving out of Hawaii than moving in. The state gained 125,160 people during the five-year period, the majority (32,321) moving to the islands from California. But 201,293 moved out of the islands. The Golden State also proved to be a popular destination for people leaving Hawaii. Of those who left, 44,192 were residing in California by 2000, the most of any destination state.