Transform faults make up a relatively small percentage of Earth's plate boundaries. While the exact percentage is difficult to quantify precisely, estimates suggest that they account for around 15-20% of the total boundary length.

Here's why:

* The majority of plate boundaries are either divergent or convergent. Divergent boundaries, where plates move apart (like the Mid-Atlantic Ridge), and convergent boundaries, where plates collide (like the Himalayas), are much more extensive than transform faults.

* Transform faults primarily connect other boundary types. They act as "slip" zones to accommodate the relative motion between diverging or converging plates.

* Examples include the San Andreas Fault in California, which connects the Pacific Plate to the North American Plate, and the Alpine Fault in New Zealand.

Therefore, while transform faults are crucial for understanding plate tectonics, they constitute a smaller portion of the overall plate boundary system.