Complex sentence: The Chilean pension "model", which has both supporters and critics, has to date been implemented by 30 countries although many of them have combined this new defined-contribution system with their former state-run, defined-benefit pension schemes.
Split into simpler sentences: The Chilean pension "model" has to date been implemented by 30 countries. Many of them have combined this new defined-contribution system with their former state-run, defined-benefit pension schemes.