"English and German score 60-65%, English and French about 20%. More
exact
figures are available in the
lexicostatistical literature. Isidore Dyen did a book a few years ago on
Indo-European subgrouping using
lexicostatistics in which you can probably find the figures he uses.
Dyen in his 'Lexicostatistical classification of the Austronesian
languages', and in other publications
from that era, uses 70% basic vocabulary cognation as the 'language
limit'
(viz. the point at which related
language communities cease being dialects of one language and become
distinct languages). "