How coverage changes
Recurring themes
Article counts by year. A dot means zero; stronger color marks the topic’s busiest years. Click a count to read the article list.
Counting and coverage
The chart keeps every topic that reaches the chosen annual top-N in any displayed year, then follows that topic across the whole period—even when it falls out of the top-N. Only annual leaders are labeled on the bands. Connections join the same theme, not individual articles or a change from one theme into another.
Primary topic means the first, highest-ranked topic in the article dataset. The alternative counts every assigned topic. Bands taper as annual counts change. In share mode, widths use all posts (primary) or all topic assignments (every topic) in that year as their denominator, including themes not shown.
The archive contains 3,949 distinct posts. The default view starts in 2009; 2008 contains one saved post and can be selected. The 2026 capture ends September 21. Article topics come from automated classification with targeted corrections. Filters and the article lists use the same saved records. Dataset methods and attribution details.