LONDON, England (CNN) -- Earlier this week, the case of Hiroki Ando, the Japanese 11-year-old boy who was denied a heart transplant in Japan, highlighted the vast cultural divide in attitudes towards organ transplant and availability worldwide. 

Hiroki plays catch at the Tokyo Women's Medical University Hospital. 

Hiroki had to travel to the U.S., where he is awaiting a heart, because Japan prohibits organ transplants involving children. 

His story highlights the wide range of policies around the world regarding organ donation. Watch Hiroki's trip to the U.S. » 

Organ donation has saved and improved countless lives. But medical advancements have led to a rise in demand for organs that is outpacing donation rates. 

Some countries, particularly Spain, have succeeded in raising the number of organ donors, but there is still much room for improvement, according to Leo Roels, managing director of the Donor Action Foundation. 

"What we see in our experience in so many countries is that there is still a lot of potential when it comes to identifying donors," he told CNN. 

The Donor Action Foundation is a non-profit group that helps hospitals implement programs designed to improve their donation rates. It's active in 17 countries worldwide. 

Looking at deceased donors per million population -- a commonly used benchmark -- rates vary widely around the world. 

Spain leads internationally with 34 deceased donors per million population, according to figures from the International Registry of Organ Donation and Transplantation. 

Australia, on the other hand, noticeably lags countries with comparable health care systems with just 12 deceased donors per million population. 
Are donation rates keeping up?
a rise in demand for organs that is outpacing donation rates