Metro requires cities to build at 80% of their zoned max density.
(This a reversal of the purpose of the original intent of zoning which was to prevent too much density.)

See Metro Code Chapter 3.07 (118k PDF file) for examples of this 80% rule:

3.07.120 Methods to Increase Calculated Capacity Required for All Cities and Counties

3.07.140 Requirements to Increase Capacity If Recent Development At Low Density