Before 2009, I was 100% DL. ( Except for intra-Asia flights)

Starting in 2009, I started splitting my business between DL and CO.

For the last 2 years...

CO - 120,000+ per year
DL - 100,000 per year

But now waiting to see how the CO/UA merger goes. With the introduction of EC, DL came back into the mix for International travel. But too much is uncertain for me to throw all of my miles at one carrier