How old is Jessie of Team Rocket?

She is 17. in the episode "holiday hi-Jynx" Jessie was rembering a flash back that happened 10 years ago and it said she was seven. also in another episode "The Ultimate Test" Jessie and Ash were filling out paper work for the test. Ash looked over at Jessie because she was staring at him, then went back to filling out the papper as she read it outloud. "age? 17."