16.
I have some history with Jirachi and why I value it so much. I got my hands on the mystery gift Jirachi in Heart gold when I was like 12. I raised it to level 100 and treasured it so, but then I made one fatal mistake. I transfered it to the pokewalker, and I forgot to take it out of my pocket before my mom washed it in the washing machine. I remember crying because I lost a pokemon I treasured so much, and to make matters worse you cannot get an event pokemon a second time. Not to mention I could no longer use the pokewalker even if I replaced the battery because Heart gold thinks I still have Jirachi. This happened several years ago, and I have since transferred my pokemon to the later gens and restarted Heart gold.