How much bandwidth does Left 4 Dead 2 use

Taken from:
https://support.steampowered.com/kb_article.php?ref=5386-HMJI-5162

128k uplink = 4 players (2 players for srcds)
256k uplink = 7 players (4 players for srcds)
320k uplink = 9 players (6 players for srcds)
512k uplink = 14 players (9 players for srcds)
768k uplink = 21 players (14 players for srcds)
1024k uplink = 28 player (19 players for srcds - note 16 players max for HL2DM)
1140k uplink = 32 players (max for HLDS) (21 players for CS:S)
1708k uplink = 32 players for CS:S (max)

A good rule for HLDS is 35.6Kbits per player.
A good rule for SRCDS (Source Games) is 53.4KBits per player.
(about 1.5x more than HLDM)