The easiest way is to present your passport showing the record of your exit and entry from the country. If you have recently renewed your passport, I suggest that you bring along your old passport as well. If they don’t stamp your passport upon exit and entry, then you need some other document to prove your residency. Utility payment slips or tax payment receipts are usually helpful. If you obtained your license when you were in school, a diploma or graduation certificate might also help.