<P> The resulting changes in the age structure of the population include a decline in the youth dependency ratio and eventually population aging . The population structure becomes less triangular and more like an elongated balloon . During the period between the decline in youth dependency and rise in old age dependency there is a demographic window of opportunity that can potentially produce economic growth through an increase in the ratio of working age to dependent population; the demographic dividend . </P> <P> However, unless factors such as those listed above are allowed to work, a society's birth rates may not drop to a low level in due time, which means that the society cannot proceed to stage Three and is locked in what is called a demographic trap . </P> <P> Countries that have witnessed a fertility decline of over 50% from their pre-transition levels include: Costa Rica, El Salvador, Panama, Jamaica, Mexico, Colombia, Ecuador, Guyana, Philippines, Indonesia, Malaysia, Sri Lanka, Turkey, Azerbaijan, Turkmenistan, Uzbekistan, Tunisia, Algeria, Morocco, Lebanon, South Africa, India, Saudi Arabia, and many Pacific islands . </P> <P> Countries that have experienced a fertility decline of 25 - 50% include: Guatemala, Tajikistan, Egypt, and Zimbabwe . </P>

Which of these statements about the availability of family-planning programs and birth rates is true