What a ridiculous statement.
Textbook example of a Type I Error.
When a Catholic falls away from the Church and doesn't live his faith any more, he generally still refers to himself as a Catholic anyway.
When an Evangelical falls away from the Christian life, he generally doesn't refer to himself as an Evangelical anymore.
That's the only difference.
The number of people who claim to have been born again at some point in their lives and the number of people who actually live a Evangelical life is as great a discrepancy as the number of people who are nominally Catholic and those who actually live a Catholic life.
Secondly, evangelicals are converting Catholics both in the US and abroad.