Evolution of the LEGO part catalog over time I have downloaded the Bricklink catalog four or five times in the past, but the interval was very irregular. I would like to look at the evolution of the LEGO part list over the years. However, I didn't find an option on Bricklink, or elsewhere on the Internet, to download past versions. 

Are you aware of any archive of Bricklink catalogs? I haven't looked at other platforms with LEGO catalogs. Any other idea to get systematic information on the evolution of the part list is also welcome, of course.
You might be able to get the information that you are after from the Rebrickable database dumps. This includes set inventories for many sets, along with the year that the sets were released. Here's the full schema diagram:



A query something like this should provide a count of the number of sets every element has appeared in by year:




SELECT year,
       Sum(1),
       colors.name,
       parts.name,
       parts.part_num,
       colors.id
FROM   sets
       JOIN inventories
         ON inventories.set_num = sets.set_num
            AND inventories.version = 1
       LEFT JOIN inventory_parts
              ON inventory_parts.inventory_id = inventories.id
       JOIN parts
         ON parts.part_num = inventory_parts.part_num
       JOIN colors
         ON colors.id = inventory_parts.color_id
GROUP  BY year,
          colors.name,
          parts.name,
          parts.part_num,
          colors.id
ORDER  BY year DESC,
          colors.name ASC 


Here's that dataset:

https://gist.github.com/jncraton/b0641ce5f8bc28e10e761a5ce1bafd51

Note that this query includes part variations (mold updates, prints, etc) as unique elements, so you may need to filter it down quite a bit for your use case. If you'd like to run your own queries directly against the full Rebrickable dataset, I maintain some scripts that make this fairly easy to do.