Complex sentence: The birth rate has recovered in recent years from a catastrophically low level around 2000, and is now comparable to the European average, but would need to increase by another 50% or so to stabilize the population and offset the high mortality rate.
Split into simpler sentences: The birth rate has recovered in recent years from a low level around 2000, and is now comparable to the European average. It would need to increase by another 50% or so to stabilize the population and offset the high mortality rate.