what the heck does this mean on nexgenwars?

on nexgenwars.com, there is a line chart, how come on the 360's line, it dips down for like a centimeter about 1/4 the way across it? did 200,000 people suddenly return their 360s all at the same time? i dont get that, did new data come in that showed a mistake?1stCommando

THERE IS YOUR ANSWER. 

on nexgenwars.com, there is a line chart, how come on the 360's line, it dips down for like a centimeter about 1/4 the way across it? did 200,000 people suddenly return their 360s all at the same time? i dont get that, did new data come in that showed a mistake?1stCommando