Why did God only cure Naaman?

Jesus said (Luke 4:27): > "There were also many lepers in Israel in the time of the prophet Elisha, and none of them was cleansed except Naaman the Syrian." Several possible interpretations occur to me: 1. Others were cured too; Jesus is simply wrong or misquoted. 2. Others were not cured. (Why?) 3. Even Naaman was not cured, because miracles are fantasy. What does the evidence say? Is there any extra-biblical source confirming Naaman's curing? Is there any explanation why the other lepers are not cured? I am mainly looking for extra biblical evidence that would convince the agnosis. After all, if Jesus says so and it were true is not an assumption we all share. Moreover, Jesus often says vague things, (like the time is near) and easily misinterpreted things, like mustard seed is the smallest.