In single-family permits, through April, there have been 4,993 permits this year, compared to 3,389 during the first four months of 2012. That's an increase of 47 percent.
During this year's the month of April alone, there were 1,408 single family permits and 343 multifamily permits issued. During April of 2012, there were 1,070 and 884 single-family and multifamily units, respectively.
The first graph shows cumulative totals from January through April of each year:
The second graph shows month to month totals in permits. Note the upward drift in both single-family and multifamily permits. Totals, of course, remain well down from peak levels. We can see in both of the first two graphs that multifamily permitting is more or less at a ten-year high and is at levels seen during periods of solid economic growth such as 2007.
In single-family, builders are responding to home price growth and limited inventory, but as RPX has pointed out, there are many factors that may contribute to growth in inventory and a moderation in home price growth.