BLEU score value higher than 1

Question

I've been looking at how BLEU score works. What I understood from the online videos + the original research paper is that BLEU score value should be within the range 0-1.

Then, when I started to look at some research papers, I found that BLEU value (almost) always higher than 1! For instance, have a look here:

• https://www.aclweb.org/anthology/W19-8624.pdf
• https://arxiv.org/pdf/2005.01107v1.pdf

Am I missing something?

Another small point: what does the headers in the table below mean? The BLEU score was calculated using unigrams, then unigrams & bigrams (averaged), etc.? or each ngrams size was calculated independently?