I'm piecing together some stats here. According to this (
http://espn.go.com/blog/statsinfo/po...-effect-on-nfl), 1374 kickoffs were returned in 2011. So 10 scores on 1374 returns, that's roughly half the scoring of corner kicks. Of course that's playoff soccer, with the best teams. I assume that if you look at regular season totals that corner kicks would result in less scoring, as the overall quality of play would be lower.