upstream_response_time

[Jeroen Ooms]

I am using

    add_header x-responsetime $upstream_response_time;

to report response times of the back-end to the client. I was
expecting to see the back-end response time (e.g. 0.500 for half a
second), however the headers that I am getting contain an epoch
timestamp, e.g:

x-responsetime: 1392070197.589

What am I doing wrong?