Basically what is see here is that the Tibetan realized that there is no future in exile and after 60 years situation just getting worse with CTA. More and more migrated to other countries is an obvious sign. For those Tibetans in China, China has invested in Tibet for rebuild and refurbishment as well and development. More Tibetan are having a good living there and there is no reason for them to leave and stay in exile. Many Tibetans know that Dalai Lama wants to stay under China and they may as well just wait in China for Dalai Lama to return.
There is nothing for CTA to blame China for the dwindling of the Tibetan population because CTA has not done their part and there is nothing great in exile for the Tibetan to move there anymore. Due to CTA mismanagement, many Tibetans are leaving CTA and you will not see anyone move over to exile to find suffering for themselves. Sadly that CTA will never able to see this and just keep blaming China for everything that is not workout in exile, India.