从一个文本文件中逐行读取一个字符串，并计算出字母a到z出现的百分比（单位：%），不区分大写和小写字母。

输出结果如图1
要求：
运用数组来分配26字母
类似图2方式逐行逐字判断
Ctrl + z后执行


图1：
图2:
测试文本如下：//LICENSE

The OpenSSL toolkit stays under a dual license, i.e. both the conditions of
the OpenSSL License and the original SSLeay license apply to the toolkit.
See below for the actual license texts. Actually both licenses are BSD-style
Open Source licenses.

This package includes materials licensed under the BSD license.
Here is the license text:

Copyright (c) 1998-2001, Robert O'Callahan
All rights reserved.

Redistribution and use in source and binary forms,
with or without modification,
are permitted provided that the following conditions are met:
Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
//