Given the following passage  "According to Johnson and Grim (2013), Buddhism has grown from a total of 138 million adherents in 1910, of which 137 million were in Asia, to 495 million in 2010, of which 487 million are in Asia. According to them, there was a fast annual growth of Buddhism in Pakistan, Saudi Arabia, Lebanon and several Western European countries (1910–2010). More recently (2000–2010), the countries with highest growth rates are Qatar, the United Arab Emirates, Iran and some African countries.",  answer the following question. Note that the answer is present within the text.  Question: When was the study on Buddhism published?
The answer to this question is:
2013