function payment_onload() {
  new Ajax.Updater("premium_subscription_repartition", "/premium/premium_subscription_repartition", {
    parameters: {period:"week"}
  })
  $$(".change_period").each(function(l) {
    new Event.observe(l, 'click', function() {
      var period = this.href.split("#")[1]
      new Ajax.Updater("premium_subscription_repartition", "/premium/premium_subscription_repartition", {
        parameters: {period:period}
      })
    })
  })
}