Result of
grep -h -R "User-Agent" /var/spool/news/gmane/**|cut -d: -f2|cut -d" " -f2|cut -d"/" -f1|sort|uniq -c|sort -gr
   1308 G2
    754 Mozilla
    738 Mutt
    308 KMail
    103 Thunderbird
     82 Alpine
     60 quilt
     54 Gnus
     17 Opera
     12 Loom
     11 Sup
     11 mutt-ng
     10 v=1;
     10 StGIT
     10 slrn
     10 Received
     10 Jack
      9 nail
      9 Mozilla-Thunderbird
      8 Notmuch
      7 Postbox
      5 Wanderlust
      5 StGit
      5 SquirrelMail
      4 Xnews
      4 Internet
      3 (X11;
      3 Pan
      3 KNode
      2 Web-Based
      2 RoundCube
      2 From
      2 curl
      2 40tude_Dialog
      1 NaSMail
      1 Heirloom
      1 Dynamic
      1 #1