My quest for continuing education led me to read a book this week on the above topic. Italian Repatriation from the United States, 1900-1914 by Betty Boyd Caroli is rife with statistics and explains this issue as seen by both the Italian and American government as well as scholars on both sides of the ocean.
Most interesting to me, was the interviews with actual immigrants who had returned. I highly suggest this book if you wish to further your understanding of this topic. The book is available on Amazon.com.