doesnt answer the question as to why budhist populations are increasing from the time of Buddah,if according to nirvana people are spposed to be perishing
1. More and more people are embracing Buddhism as they find inner peace when living according to it and it is based on fact and reason.
2. There are an unimaginably high number of beings existent (not only on earth, in different worlds). They are born on earth when their Karma is right. You possibly can't compare such a big number (think billions of billions of billions of billions) with the comparatively minute population on the earth.
No, only a minority attained Nibbana even in Buddha's day, and almost none now (at least I don't know of any)






