请帮忙翻译一段话，关于英国养老金缴纳 Employees pay contributions on all of their earnings above the ET（Earnings Threshold）. They pay at a main percentage rate on earnings up to the Upper Earnings Level (UEL) and at a lower percentage rate on all earnings above the UEL. 超过收入上限的部分，究竟是如何缴费的？谢绝GOOGLE翻译。