汗牛充栋

shì jì chū yè yǐ lái zhì xiàn zài xī fāng jīng jì zhōu qī lǐ lùn jiǎ shuō yǐ jīng hàn niú chōng dòng

19世纪初叶以来至现在，西方经济周期理论假说已经汗牛充栋。

From early 19th century till now, there has been a lot of theoretical hypotheses on economic cycle in western countries.