Deaths really aren't too important on supports, as long as they're meaningful. If your team can capitalize off of your death, it's worth it and it's better you sponge the deaths than a carry. Now if you're playing an offensive support like Zyra or Brand, you really do want to mitigate your deaths overall, as your filling a role of an additional carry. If you're dying a lot as a damage dealing support, you're not contributing to anything for your teamfights.
What I look for in supports is ward stats, while comparing deaths to damage received. If you're a tanky champion, you want it to show a lot of damage received typically. If you're an offensive support, you want your damage received stat to be as low as you can, while maintaining a comparable damage given stat. Factor in deaths accordingly.