【教えて下さい】「median daily usaji」の意味

Meanwhile, a maximum allowable fluctuation of the yuan against the dollar was pegged at 0.3% per day either way of a median rate of the yuan. (The yuan’s maximum permissible daily fluctuation against other currencies was set at 1.5% either way of its median rate. The fluctuation range was later expanded to 3% either way.)
他方、変動幅については、これまでと変わりはなく、中心レートから１日に±0.3％以内（対ドルレート、他の通貨は±1.5％以内、後に±３％）とされた。 - 経済産業省
http://ejje.weblio.jp/sentence/content/median+daily