If you want my view , I will say, after death within 24 hours body is destroyed in Agni as Hindu belief human body creates with ( पांच तत्व से ) so after death it should go to that five elements ( Agni , Bayu , Pani , Mitti and Akash ). Hindu also believe if body will be destroyed then soul will not possible to enter again and after 11 days it goes to hell or heaven as per his karma. Mainly good soul never re – birth that’s way Hindu birth ratio reducing day by day. On the other side Muslim or Christian never believe hell or heaven. They only beleive if they destroy other dharma then Allaha or Jesus wil give good fortune, lot of wealth and women. They also preserve the dead body in coffin and bury inside earth. Their souls are not free from karma and soon they get re birth. That is reason there ratio of births is high.
Other religions may not believe in rebirth.But other religion souls are over packed in Hell creating a storage problem for us. We should think of a way for disposal of these souls.