Dividend Yield - Boom/Bust

In boom periods less dividends are paid out, the D.Y (D/P) lowers.

In times when the economy is uncertain the D.Y increases. Why? If we look at the formula is this number increasing solely because price falls leaving a larger numerator? Or do dividends actually increase in these cimates - it seems counter intuitive to increase dividends when the economy is poor as surely companies want to retain earnings.

The former, most likely.