The category that eats the chart

site on clinical-trial has 6 values, and one of them is 19.3% of the data.

• site-2 — 174 rows, 19.3%
• site-4 — 152 rows, 16.9%
• site-3 — 148 rows, 16.4%
• site-6 — 146 rows, 16.2%
• site-1 — 142 rows, 15.8%

The top three take 52.7% between them. With only 6 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(baseline_score)::numeric, 2)             as avg_baseline_score
from clinical_trial
group by 1
order by rows desc;

The second column is the one that matters. Share of rows tells you what is common; avg_baseline_score 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.