Under the Linux operating system, the "xanim" program shows these GIF files nicely. It is also possible to use browsers to view them. Some PC software can't handle such large animated GIFs, so if you find software that works well, please [report the name of the software you used].
Each month is available as a compressed GIF file or as a plain GIF file. The compression is GZIP compression, which many browsers can automatically unencode.