Yours truly came across a news article indicating that Santa Monica College provided more undergraduate transfers to UC than any othre community college. You can find the article at:
So he poked around the website for the community college system to find out which community colleges led in transfers to UCLA. The pie chart above shows the results for all community colleges providing at least 100 transfers in academic year 2012-13. [Click on the chart to enlarge and clarify.] More than half of the transfers came from colleges providing under 100 students. Santa Monica was again the leading transfer institution with Pasadena a distant second. FYI.