I have been working on two projects for last one year or so and they are almost done. But this month my postdoc tenure ended. So I have just joined another institute as a postdoc. Should I put both institute affiliations on the papers? I feel a bit 'uncomfortable' to put only the current affiliation since more than 90% of the work was done while I was in my previous institute.

I am in theoretical high energy physics. I don't think people care about these issues, but I would like to know the norm.