| | Cos Cob, CT | Country Knolls, NY | United States |
| Median Home Age | 60 | 43 | 42 |
| Median Home Cost | $1,121,400 | $340,100 | $338,100 |
| Home Appr. Last 12 months | 15.3% | 11.8% | 16.6% |
| Home Appr. Last 5 yrs. | 40.9% | 39.6% | 57.0% |
| Home Appr. Last 10 yrs. | 46.6% | 49.3% | 101.1% |
| Property Tax Rate | $18.4 | $17.6 | $11.0 |
| Homes Owned | 66.1% | 93.4% | 57.4% |
| Housing Vacant | 2.7% | 2.7% | 11.2% |
| Homes Rented | 31.2% | 3.8% | 31.4% |
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| Avg Rent For Home Or Apartment | | | |
| | Cos Cob, CT | Country Knolls, NY | United States |
| Average Rent | $3,230 | $1,690 | $1,840 |
| Studio Apartment | $1,750 | $1,040 | $1,080 |
| 1 Bedroom Home or Apartment | $2,130 | $1,160 | $1,180 |
| 2 Bedroom Home or Apartment | $2,610 | $1,410 | $1,430 |
| 3 Bedroom Home or Apartment | $3,280 | $1,720 | $1,860 |
| 4 Bedroom Home or Apartment | $3,610 | $1,890 | $2,160 |
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| Vacant Housing | | | |
| | Cos Cob, CT | Country Knolls, NY | United States |
| Vacant For Rent | 0.3% | 0.0% | 1.9% |
| Vacant Rented | 0.0% | 0.0% | 0.4% |
| Vacant For Sale | 0.9% | 0.0% | 0.7% |
| Vacant Sold | 0.3% | 0.8% | 0.4% |
| Vacant Vacation | 0.0% | 0.5% | 3.6% |
| Vacant Other | 1.1% | 1.5% | 4.1% |
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| Owner-Occupied Housing Value | | | |
| | Cos Cob, CT | Country Knolls, NY | United States |
| Less Than $20,000 | 0.6% | 0.9% | 2.6% |
| $20,000 to $39,999 | 0.0% | 0.4% | 2.4% |
| $40,000 to $59,999 | 0.0% | 0.0% | 2.8% |
| $60,000 to $79,999 | 0.0% | 0.0% | 3.9% |
| $80,000 to $99,999 | 0.0% | 0.0% | 4.5% |
| $100,000 to $149,999 | 0.0% | 1.1% | 11.3% |
| $150,000 to $199,999 | 2.2% | 6.4% | 13.0% |
| $200,000 to $299,999 | 0.7% | 40.2% | 20.1% |
| $300,000 to $399,999 | 0.8% | 42.7% | 13.6% |
| $400,000 to $499,999 | 1.5% | 5.6% | 8.3% |
| $500,000 to $749,999 | 15.9% | 2.4% | 9.7% |
| $750,000 to $999,999 | 27.0% | 0.4% | 3.9% |
| $1,000,000 to $1,499,999 | 31.1% | 0.0% | 2.2% |
| $1,500,000 to $1,999,999 | 14.7% | 0.0% | 0.8% |
| $2,000,000 and over | 5.4% | 0.0% | 1.1% |
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| Housing Units By Year Built | | | |
| | Cos Cob, CT | Country Knolls, NY | United States |
| 2015 and Newer | 0.0% | 0.0% | 0.2% |
| 2010 to 2014 | 5.5% | 8.3% | 13.6% |
| 2000 to 2009 | 5.5% | 8.3% | 13.6% |
| 1990 to 1999 | 5.8% | 5.0% | 13.6% |
| 1980 to 1989 | 10.1% | 30.3% | 13.2% |
| 1970 to 1979 | 13.3% | 36.1% | 14.8% |
| 1960 to 1969 | 5.8% | 5.0% | 13.6% |
| 1950 to 1959 | 17.5% | 1.0% | 10.0% |
| 1940 to 1949 | 2.9% | 0.8% | 4.7% |
| 1939 or Earlier | 28.2% | 1.9% | 12.2% |