We tend to think of demographics on a large scale. Countries, counties, and cities. Then we look at trends over time for thousands or millions of people. But it can be equally, if not more, interesting to look at the same trends at a personal level. This is what Dorothy Gambrell did. She charted her ten closest friends in New York.
I like how even though the charts are for only ten people, we see similar patterns that we might see for millions.