How much has our knowledge of the stellar neighborhood improved?

This project must be done by individuals.

Astronomers have worked very hard to measure the distances to stars in the sky. For several hundred years now, scientists have always been pushing the limits and running surveys as large as they can afford.

How much has our knowledge of the very nearest stars -- the ones which should be easiest to find and measure -- changed over a few decades? Let's find out.

In 1979, Guy Ottewell published a very pretty illustrated book, The Astronomical Companion. In a section which discusses the nearest stars, he writes the following, using the best available catalog of nearby stars.

Based on this small excerpt, answer the following two questions:

As of 1979, how many stars had astronomers found within a radius of 6.5 pc?
As of 1979, how many stars had astronomers found within a radius of 20 pc?

Now, what about our best catalog of nearby stars in the current day, about 46 years after Ottewell's statement. The current best is the Gaia DR3 archive, which you can access freely on-line, either directly by using the "Search" tab in the above URL, or indirectly at Vizier, via the Gaia DR3 Part 1: Main source webpage. If you aren't sure how to use these resources, please visit my office hours; I'll be happy to show you.

According to Gaia, how many stars lie within 6.5 pc of the Sun? Please require that the measurement be a good one, to eliminate the small number of "fake" stars which appear in the catalog due to noise; you can get rid of some "fake" stars by requiring that the "RPlx" value be greater than 10.
Compare the numbers within 6.5 pc known in 1979 and known in 2025. Is there any big difference?
According to Gaia, how many stars lie within 20 pc of the Sun?
Compare the numbers within 20 pc known in 1979 and known in 2025. Is there any big difference?

Ottewell does a calculation to look for incompleteness: he calculates the ratio of VOLUME between a 20-pc and 6.5-pc sphere, and compares it to the ratio of STARS FOUND within those two spheres. If the density of stars is uniform in space, the two ratios should be the same.

In 1979, the ratios were 29 times more volume, but only 10.4 times as many stars. Such a large difference was a sign that our catalogs were missing lots of stars beyond 6.5 pc.

What is the ratio of these two quantities now, using the Gaia DR3 catalog to count stars?
Do you think our current catalog of stars is complete out to 20 pc?
How large is the Milky Way Galaxy? What do you think of our catalogs of stars throughout the entire galaxy?