Matt, what are you talking about?
Thai stats: First quarter arrivals in 2018 up by 15.4 % compared to previous year (10.61 million arrivals)
Total number of visitors to Thailand increased from 32.59 million in 2016 to 35.38 million in 2017.
The title of this thread is TG - the two letter code for Thai Aiways. Not all tourists arrive on Thai planes.