给出一个英文文本，并使用TF-IDF算法计算文本中每个单词的重要性。
"Natural language processing (NLP) is a subfield of computer science, artificial intelligence, and computational linguistics concerned with the interactions between computers and human languages, in particular how to program computers to process and analyze large amounts of natural language data."
TF-IDF is a technique used to analyze the importance of words in a text document. The importance of a word in a document is determined by multiplying the term frequency (TF) and the inverse document frequency (IDF) of the word. 

In our example text, the important words in decreasing order of their TF-IDF scores are: natural, language, processing, NLP, subfield, computer, science, artificial, intelligence, computational, linguistics, concerned, interactions, human, languages, program, process, analyze, large, amounts, and data.