The United Kingdom is having to import sperm stocks from abroad due to a serious shortage of donors in Britain, the Human Fertilization and Embryology Authority has warned.

According to a report from the group, imports make up almost a quarter of donated samples in Britain. It's thought that native donations dropped considerably thanks to the dropping of a clause that would have offered total anonymity to donors in 2005. Back in '05, imports made up just one in ten samples in Britain.
The majority of these are from the United States and Denmark, with the latter country being home to the biggest sperm bank in the world. You can check out the official British government records here, should you want to for any reason.