Parents of Ranni Iversdatter

I woud like some help locating the birth and thus the parents of Ranni Iversdatter born about 1750 in Vest-Agder. She is listed in the 1801 Census along with her husband Ole Larsen Butveit and their two daughters. I have looked at the pages for Bjelland from 1749 to 1751 with no luck. That doesn't mean that she is not there as the writing from those particular pages is extremely difficult for me to read. Here is a link to the census. http://digitalarkivet.arkivverket.no/ft/person/pf01058339002249