Original sentence: Additionaly it is estimated that 20 percent of converts to Islam unconvert from Islam within a few years.In Dec 2000 the Islamic media network Al-Jazeera  reported that  a significant number of Muslims are converting to Christianity in Africa at the rate of over 6 million a year.There are approximately 5 million Muslims in North America.This is mainly due to the higher birth rates in many Islamic countries; a high conversion rate may also be a factor
Edited sentence: There are approximately 5 - 6 million Muslims in North America.This is mainly due to the higher birth rates in many Islamic countries while a high conversion rate may also be a factor