jiǔ niú yì máo

九牛一毛

a single hair out of nine ox hides

a drop in the bucket (or ocean); too little to make a difference; insufficient

Example:

电子商务的盈利在中国整体商业环境中简直是九牛一毛
diànzǐ shāngwù de yínglì zài zhōngguó zhěngtǐ shāngyè huánjìng zhōng jiǎnzhí shì jiǔniúyìmáo
In the entire Chinese commercial environment, the profits from E-commerce are simply just a drop in the bucket