Pregnancy after vasectomy

How common or uncommon is a pregnancy after a vasectomy? Our Dr told us it's only guaranteed for 5 yrs. We are already going into year 3. Have heard many stories of pregnancies after vasectomies but when I look at the stats and percentages on multiple sites, it says it's extremely rare. I just don't believe that. I don't think it's that rare to be honest. God's plans always go over ours anyways so if it's His will for us to conceive, his vasectomy won't even matter.