Nearly 71% of the members _______ in favor of the policy.

Fraction (One-third/Two-thirds of) + singular/uncountable noun + singular verb.
Fraction (One-third/Two-thirds of) + plural noun + plural verb.
Nearly 71% of the members are in favor of the policy.
Nearly 71% of the time is used in preparing the plot.
Nearly two-thirds of the members are in favor of the policy.
Nearly two-thirds of the time is used in preparing the plot.