To me, one of the best ways to measure progress is to look at the number of children dying from preventable causes. And today, more kids are living to see their 5th birthday than ever before. This year, for at least the 42nd year in a row, the child mortality rate has fallen. And it’s not just moving in the right direction — it’s falling faster than anyone expected. The Economist estimates that the world has saved 13.6 million children’s lives since 2001. It’s hard to think of a better sign that the world is improving.