The numbers on the graph reflect how many searches have been done for
a particular term, relative to the total number of searches done on

because the data is normalized and presented on a scale from 0-100;
each point on the graph is divided by the highest point, or 100.
Basically Google Insight is an advanced version of Google Trends.
Google Trends:
Google Trends analyzes a portion of Google web searches to compute how
many searches have been done for the terms you enter, relative to the
total number of searches d

graph with the results -Search Volume Index graph. This graph shows
you the number of times your topic appeared in Google News stories.
When Google Trends detects a spike in the volume of news stories for a
particular search term, it labels the graph and displays the headline
of an automatically selected Google News story written near the time
of that spike.
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