Generate a question which can yield the answer mentioned in the input. Generated question must be answered by the answer provided in input, without using any extra knowledge.

Context : The ZBD-97, or Type 97, has been in service with the PLA ground forces since 2006, in the armored units of the Guangzhou and Nanjing military regions.
Answer : 2006
What year was the service entry date for ZBD-97?