计算文本中各个单词出现的频率，并按照频率从高到低输出。


This is a sample sentence to count the frequency of each word in this text.
is: 1
sample: 1
to: 1
count: 1
the: 3
frequency: 1
of: 1
each: 1
word: 1
in: 1
text: 1
this: 2
sentence: 1
from: 1
high: 1
down: 1
and: 1
output: 1

按照频率从高到低输出：
the: 3
this: 2
is: 1
sample: 1
to: 1
count: 1
frequency: 1
of: 1
each: 1
word: 1
in: 1
text: 1
sentence: 1
from: 1
high: 1
down: 1
and: 1
output: 1