割
カツ, わ.る, わり, わ.り, わ.れる, さ.く

proportion, comparatively, divide, cut, separate, split

JLPT3 G6 S12 F318

As per 害# (cut) + 刀 sword/knife → sharp implement used in cutting/separating → *separation*; *division*; *breakage* → *cut*; *split*; *divide*; *break*; *crack open*; *dilute*; *drop below* (a standard) → *rate*; *ratio*; *percentage*; *allocation*; *comparatively*. Also, *find out* (← figuratively crack open a criminal's hiding place).

[Full Kanji Etymology List]