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Paraphrasing from the Physiological Basis of Physical Education and Athletics by Mathews and Fox:

The distribution of fast and slow twitch fibers varies greatly from person to person, and from type of athlete to athlete. For instance, a long distance runner has a greater amount of red (slow or type I) twitch fibers than does the sprinter who has a breater number of white (fast or type II) twitch fibers. As a matter of fact certain muscle groups are predominantly red or white. For example the gastrocnemius, lats, biceps, and delts and mostly white fibers. While on the other hand the rectus femoris, soleus, semitendinosus (one of the hamstring muscles) and the rectus abdominis (the six-pack) are mostly red fibers.

Here is a common (and approximate) distribution of red and white fibers and max VO2 (maximal oxygen comsumption) for different groups of people:

Untrained: 64% white, 36% red, max VO2: 43 mL/kg-min
weight lifters: 50% white, 50% red, max VO2: 40 mL/kg-min
runners: 40% white, 60% red, max VO2: 72 mL/kg-min
Canoeists: 39% white, 61% red, 56 mL/kg-min
Bicyclists: 38% white, 62% red, 68 ml/kg-min
swimmers: 33% white, 67% red, 80 mL/kg-min

Notice how the higher amount of red fibers, the higher the max VO2 is. This is because the red fibers are aerobic and use oxygen for power.

(adapted from the Physiological Basis of Physical Education and Athletics by Mathews and Fox, Copyright 1976 by the W. B. Saunders Company)