The population of Bangkok is over 5.7 million, or 8.9% of the country's population [30]. Family size has become smaller. In 1960, there were 6.2 people per family compared to 2.3 in 2005. The numbers of children and people of working age declined, while the elder population steadily increased (Fig. 2). It is projected that the elder population (aged 60 and older) will exceed the population of children (aged less than 15 years) in 2020 [3].