（二）生成200个学生成绩数据，统计不及格、及格、中等、良好和优秀的占比

以下是生成200个学生成绩数据，统计不及格、及格、中等、良好和优秀的占比的Python代码：

import random

grades = []
for i in range(200):
    grades.append(random.randint(0, 100))

excellent = 0
good = 0
medium = 0
passing = 0
failing = 0

for grade in grades:
    if grade >= 90:
        excellent += 1
    elif grade >= 80:
        good += 1
    elif grade >= 70:
        medium += 1
    elif grade >= 60:
        passing += 1
    else:
        failing += 1

total = excellent + good + medium + passing + failing

print("优秀：{:.2%}".format(excellent / total))
print("良好：{:.2%}".format(good / total))
print("中等：{:.2%}".format(medium / total))
print("及格：{:.2%}".format(passing / total))
print("不及格：{:.2%}".format(failing / total))