Tracking DNA rates — 15-18% without reminders, 7% with them

did not appreciate how high dna rates are in healthcare until i started tracking our own data properly. without reminders we sit around 15–18%. with reminders that drops to roughly 7%. for a small clinic that's not a small difference in revenue or patient care. are those numbers consistent with what other small private practices see? and what reminder system gets you the best results?