I am doing some research on WiFi for my school and one question I want to answer is what encryption is the most used. One day it was of course WEP and now it is WPA2 I assume, but it would be great if someone knows a recent source with percentages.
WiGLE.net is a site where people upload information about WiFi access points they've discovered. It's not complete, but it's a very large survey that should at least show you the trends you are interested in. This table is from their current stats page:
Wireless Encryption WPA2: 171,834,316 (56.37%) WPA: 23,980,785 (7.87%) WEP: 29,492,258 (9.68%) ????: 60,103,751 (19.72%) None: 19,818,038 (6.50%)