题目:统计平均成绩中'60分以下','60-70','70-80','80-90','90分以上'这5个分数段人数
分数列表:[85, 72, 82, 83, 89, 78, 61, 90, 75, 85, 84, 74, 84, 82, 84, 28, 82, 84, 74, 44, 45, 58, 89, 81, 48, 62, 31, 68, 78, 75, 73, 87, 86, 77, 58, 70, 57, 69, 73, 79, 79, 62, 84, 88, 82, 35, 71, 76, 54, 59, 80, 49, 66, 56, 66, 69, 84, 61, 67]