When was the great age of migration?

Jürgen Osterhammel writes:

Between 1815 and 1914 at least 82 million people moved voluntarily from one country to another, at a yearly rate of 660 migrants per million of the world population.  The comparable rate between 1945 and 1980, for example, was only 215 per million.

That is from The Transformation of the World: A Global History of the Nineteenth Century.  Here is my first post on the book.