According to the Census Bureau's year-to-date total through December 2013, the most active counties for single-family permits in Colorado, when adjusted for each County's total household numbers, were Douglas, Broomfield, Larimer, Weld, and El Paso counties.
All counties, when adjusted for the existing number households in each county: (New single-family permits per household (x1,000)):
El Paso 11.7
Of the 13,678 new single-family permits issued this year through December, 75 percent were issued in Arapahoe, Denver, Douglas, El Paso, Larimer, and Weld counties alone. 20 percent of all single-family permitting was reported in El Paso County alone. Much of the development being seen in Weld County is in the southern part of the county, and the high development rates in Douglas, Broomfield, and Larimer counties are to be expected as those areas are among the most in demand areas in the state right now for real estate in general.
New single-family permits during January-December 2013:
El Paso 2,836
(Note: All permits discussed in this article are single-family permits.)
Among metropolitan counties, the largest year-over-year (2012-2013) increases in single-family permit activity were found in Broomfield (111 percent), Weld (35 percent), and Larimer (31 percent). Pueblo reported a year-over-year decline in single-family permits with a drop of 8.1 percent. Most metro counties reported increases in the 19 percent to 25 percent range.
See here for full data.