You will be given a definition of a task first, then some input of the task.
This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.

Passage: Greece is a developed country with an economy based on the service (82.8%) and industrial sectors (13.3%). The agricultural sector contributed 3.9% of national economic output in 2015. Important Greek industries include tourism and shipping. With 18 million international tourists in 2013, Greece was the 7th most visited country in the European Union and 16th in the world. The Greek Merchant Navy is the largest in the world, with Greek-owned vessels accounting for 15% of global deadweight tonnage as of 2013. The increased demand for international maritime transportation between Greece and Asia has resulted in unprecedented investment in the shipping industry. Question: How many international tourists visited Greece in 2013?
Output:
18 million