Again (cf above) making \s match multiple whitespace -- tabs or spaces, to judge from OP - is easily handled with a "+" after the second \s.

The point about the possibility of single word "text chunks" is well made... so long as the words "pretty specific regex" are not intended to deprecate specificity.

IMO, specificity is *GOOD* in a regex unless ambiguity (or at least, specific generalizations) are required because a less-than-specific regex can lead to hard-to-find problems where the source data includes unexpected content.

Consider,

H₂O     60%
or
Grand Canyon³     70%
or
Teller-Bose condensate     50%

Does one want the "water" entry or the footnoted "Grand Canyon" in the output?