Wǒ de gòngxiàn hé tā de xiāngbǐ, zhǐshì jiǔniúyīmáo.
My contribution compared to his is just one hair out of nine oxen.
Tips
history
From Sima Qian's 《报任少卿书》 (Han dynasty): if he were executed, it would be "like losing one hair from nine oxen" — worth no more than an ant's life. Written after he chose castration over death to finish the 《史记》.
memory
Nine oxen × countless hairs each — losing one is imperceptible. English "drop in the bucket" captures the same ratio.