This year? last week? always? but it doesnt matter:
What you'll find is 50% goes over 50% goes UNDER. There wont be an apparent edge... that is unless you start Capping and finding that 60 point totals tend to go OVER, if the 2 team's involved are passing teams and the defenses are below average and UNDER if top defenses are involved etc etc.
There is no easy answer in Sports betting, you have to work hard at your number crunching.