100 Perfect Push ups (10:59)

Didn't keep track of my splits but I spent more time doing push ups and less time running.  I was on pace for 10:30 until the second to last set of push ups.  I was getting about 30-sec for 20 push ups and 2-min for each 400 meters (including time to catch breath before more push ups).  Got 25-20-20-18-18 push ups.  First two sets were great.  Last three were a struggle.  Last set I was doing two and three at a time with a quick pause between for a break.  I'm wondering if just trying to do 5 sets of 20 would make those any easier.  Then I might get to focus on my run time splits and really bring my time down....hmmmm....gotta love the way CrossFit messes with your head...LOL