Create per-chapter reports on the HA website

[rviscomi]

With the Web Almanac queries running on a monthly basis, we'll need a way to visualize the results on httparchive.org.

Reports should mirror the organization of Web Almanac chapters. So for example, the Markup report should have stats and trends for all Markup chapter metrics:

• most popular doctypes
• median page size
• adoption of content encoding schemes
• etc

The current supported data viz types are histograms and timeseries. Web Almanac charts tend to focus only on the current year so we would need to augment the histograms with more data viz types as needed, for example bar charts and leaderboard tables. Trending these over time would also require rethinking new kinds of timeseries charts that go beyond percentiles for desktop and mobile.

This is a significant project and may require its own subcontractor.