How often do your kids get a sv? Every year?

Last year was my oldest DD's first year in school full time. She caught one in February, and everyone else caught it too. She caught another one in May, and her little sister and my husband caught it (hubby got it mildly this time, he just felt off for 3 days, no other symptoms, but my littlest girl had it quite bad....I avoided it that time). I'm hoping we only get one this year, if any at all....though I don't think we'll be that lucky to avoid it altogether.