UK Statistics
Each year only about 350 children from all over the world are adopted into the UK, this is the lowest rate in Europe.
Source
http://www.internationaladoptionguide.co.uk/

Why is it the lowest rate in Europe?

I will look at the stats fir the US in the next post.

You are not alone when adopting internationally, here are some statistics:

Over the last decade, U.S. families have adopted on average approximately 20,000 children from foreign nations each year.
Source
http://adoption.state.gov/adoption_process/what.php

How important is International Adoption to you?

The stats for the UK are mentioned in the previous post