Investigate CO₂ measurements and their coverage

Try this

Select the 1990s in the decade chart, then one month in the box plot; all peer views should reflect their intersection.
Select Missing in coverage. The table should retain null CO₂ records while numerical concentration marks disappear.
Clear all selections and compare the row count with the full data.

Limits

This is the historical flask-data revision distributed with statsmodels, not the latest NOAA series. Missing weeks stay null. Weekly observations at one station are not global spatial measurements.