Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 21

Sanskrit:

धर्मश्चतुष्पान्मनुजान् कृते समनुवर्तते ।स एवान्येष्वधर्मेण व्येति पादेन वर्धता ॥ २१ ॥

ITRANS:

dharmaś catuṣ-pān manujānkṛte samanuvartatesa evānyeṣv adharmeṇavyeti pādena vardhatā

Translation:

O Vidura, in the Satya millennium mankind properly and completely maintained the principles of religion, but in other millenniums religion gradually decreased by one part as irreligion was proportionately admitted.

Purport:

In the Satya millennium, complete execution of religious principles prevailed. Gradually, the principles of religion decreased by one part in each of the subsequent millenniums. In other words, at present there is one part religion and three parts irreligion. Therefore people in this age are not very happy.