Chart assignment

Charts to read and discuss

Read each chart, then answer its questions. Every chart shows its source and date; open it for a table of the numbers and the data to download.

  1. How many clinical trials start each year?
  2. Where does US electricity come from?

Chart 1 of 2 · Clinical trials

How many clinical trials start each year?

The interactive chart needs JavaScript. The numbers are on the chart's page.

About 31,100 clinical trials registered on ClinicalTrials.gov started in 2025, up from about 11,900 in 2008 and 1,900 in 2000, the registry's first year. Early years count fewer trials because registering wasn't required until medical journals asked for it in 2005 and a U.S. law did in 2007; late registrations still add a few to recent years. ClinicalTrials.gov lists trials from around the world, not only the U.S.

Questions to discuss

  1. In one sentence of your own, what does this chart show?
  2. Find the biggest change or difference in the chart. What might explain it?
  3. Who collected these numbers, and how recent are they? What else would you want to know before drawing a conclusion?

Source: ClinicalTrials.gov (U.S. National Library of Medicine), counted with its API v2 (Public domain (U.S. government work); source National Library of Medicine) · Data as of Nov 4, 2026

Open the chart and its numbers

Chart 2 of 2 · Energy

Where does US electricity come from?

The interactive chart needs JavaScript. The numbers are on the chart's page.

In 2025 natural gas made 40.8% of US electricity, followed by nuclear (17.7%) and coal (16.6%). Wind made 10.5% and solar 6.7%. Solar counts only utility-scale plants, not rooftop panels, and the 2025 figures are preliminary.

How to read this chart

Each bar is one energy source's share of all the electricity made in the U.S. in a year, so the bars add up to about 100%. The bars start at zero, so a bar twice as long means twice the share. Solar counts only large power plants, not panels on rooftops.

Questions to discuss

  1. Which source makes the most electricity? About how many times more than the smallest bar?
  2. Which of these sources burn fuel and which don't? What share of electricity comes from each group?
  3. Why might a chart of this kind look different in your state than for the whole country?

Source: U.S. Energy Information Administration, Monthly Energy Review (Table 7.2a) (Public domain (U.S. government work)) · Data as of Dec 31, 2025

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