The total outgoing traffic of ftp.fau.de increased from 4.12 PiB in 2020 to 5.04 PiB in 2021, an increase of 22%.

Rank	Mirror	Traffic 2021 in TB	Rank/Traffic 2020 (for comparison)
1	mint/iso	849	2 / 389
2	kiwix (offline Wikipedia)	519	1 / 538
3	fdroid (Free and Open-Source Android app repository	304	5 / 242
4	qtproject (Qt Toolkit)	275	4 / 356
5	gimp	266	3 / 376
6	lineageos (Free and Open-Source Android distribution)	199	6 / 204
7	eclipse	193	– / 99
8	fedora	186	8 / 148
9	opensuse	175	10 / 108
10	centos	160	7 / 159

The percentage of IPv6 traffic stagnated, with 27% (1.36 PiB), after 27% in 2020, 25% in 2019, 22% in 2018, 22% in 2017, 14% in 2016 and 11% in 2015.

There is very little change in the Top 10 overall. Sure, some mirrors got a little more or less traffic, and thus changed position in the Top 10, but fluctuations are little and nothing really stands out.

The biggest change is with mint/iso, which already was in the Top 10 on Rank 2 last year, but assured Rank 1 in 2021 quite clearly, with a large gap to Rank 2. We are not sure what caused the traffic increase for that mirror, our best guess is that they changed their download-page to prefer Torrents with webseeds, thus we are now seing a certain percentage of each download.