The category that eats the chart

site on sensor-telemetry has 3 values, and one of them is 35.3% of the data.

• NOR — 2,823 rows, 35.3%
• SLT — 2,822 rows, 35.3%
• RIV — 2,355 rows, 29.4%

The top three take 100.0% between them. With only 3 values there is no tail to worry about, which makes this a genuinely easy column to chart.

select site,
       count(*)                                      as rows,
       round(100.0 * count(*) / sum(count(*)) over (), 1) as pct,
       round(avg(temp_c)::numeric, 2)             as avg_temp_c
from sensor_telemetry
group by 1
order by rows desc;

The second column is the one that matters. Share of rows tells you what is common; avg_temp_c tells you whether the common thing is the important thing. They disagree more often than not, and a chart that shows only the first is answering the easier question.

Decide what happens to the tail before you plot it. "Other" as an explicit bucket is honest; twelve slivers is not, and neither is silently taking the top eight.