SB 3.11.21

dharmaś catuṣ-pān manujān
 kṛte samanuvartate
sa evānyeṣv adharmeṇa
 vyeti pādena vardhatā
dharmaḥ — religion; catuḥ-pāt — complete four dimensions; manujān — mankind; kṛte — in the Satya-yuga; samanuvartate — properly maintained; saḥ — that; eva — certainly; anyeṣu — in other; adharmeṇa — by the influence of irreligion; vyeti — declined; pādena — by one part; vardhatā — gradually increasing proportionately.
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.

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.