The good news for and about senior citizens is that there are a lot of us, both in raw numbers and as a proportion of the population. That trend began a couple of centuries ago, accelerated in the 20th century, and will continue for several years until the last of the baby boomers join the ranks of us old folks. Reasons for the growing numbers of seniors are many, including better nutrition, better sanitation, immunization against deadly diseases, antibiotics and other life-saving medicines and other revolutionary developments in health care.