The Office Of Federal Housing Enterprise Oversight (OFHEO) has a website that lists all kinds of information regarding housing and the changes in housing prices. You can go to the site and run reports for various areas around the country.
I ran a report for the Oxnard-Thousand Oaks-Ventura area. I graphed the results. This graph represents the one-year percentage change in housing prices for the previous quarter. For instance, in Q1 2007 the housing prices in this group decreased by 2.08% over the same quarter in 2006. This represents the first decrease since 1996. I have attached a chart for a quick visual of the trends over the past 30 years. Right now we are in the middle of the worst decline since the late 80s and early 90s.
The recent decline does not mean that houses have decreased in value by such a significant amount. What the graph shows is that the rate of change in housing prices have changed. In 2003 housing increased by 32% over the previous year, whereas in 2007 housing DECREASED by 2% over the previous year.
Click the chart for a larger view.

And here are the raw numbers that I used to plot the graph.
| Qtr |
% |
| 1978 Q1 |
28.6 |
| 1978 Q2 |
20.76 |
| 1978 Q3 |
16.43 |
| 1978 Q4 |
16.06 |
| 1979 Q1 |
13.66 |
| 1979 Q2 |
15.91 |
| 1979 Q3 |
18.35 |
| 1979 Q4 |
17.48 |
|
| Qtr |
% |
| 1980 Q1 |
21.82 |
| 1980 Q2 |
17.55 |
| 1980 Q3 |
15.83 |
| 1980 Q4 |
13.78 |
| 1981 Q1 |
7.42 |
| 1981 Q2 |
5.59 |
| 1981 Q3 |
8.99 |
| 1981 Q4 |
8.99 |
| 1982 Q1 |
6.58 |
| 1982 Q2 |
6.05 |
| 1982 Q3 |
-2.89 |
| 1982 Q4 |
-0.78 |
| 1983 Q1 |
1.29 |
| 1983 Q2 |
3.02 |
| 1983 Q3 |
8.2 |
| 1983 Q4 |
3.53 |
| 1984 Q1 |
5.56 |
| 1984 Q2 |
6.27 |
| 1984 Q3 |
2.64 |
| 1984 Q4 |
6.25 |
| 1985 Q1 |
5.75 |
| 1985 Q2 |
4.18 |
| 1985 Q3 |
6.81 |
| 1985 Q4 |
5.69 |
| 1986 Q1 |
6.85 |
| 1986 Q2 |
7.93 |
| 1986 Q3 |
8 |
| 1986 Q4 |
9.38 |
| 1987 Q1 |
10.87 |
| 1987 Q2 |
11.66 |
| 1987 Q3 |
13.11 |
| 1987 Q4 |
14.86 |
| 1988 Q1 |
16.38 |
| 1988 Q2 |
18.54 |
| 1988 Q3 |
22.85 |
| 1988 Q4 |
27.58 |
| 1989 Q1 |
29.03 |
| 1989 Q2 |
29.27 |
| 1989 Q3 |
24.04 |
| 1989 Q4 |
14.93 |
|
| Qtr |
% |
| 1990 Q1 |
8.52 |
| 1990 Q2 |
1.41 |
| 1990 Q3 |
-2.62 |
| 1990 Q4 |
-4.68 |
| 1991 Q1 |
-6.66 |
| 1991 Q2 |
-5.75 |
| 1991 Q3 |
-5.28 |
| 1991 Q4 |
-3.05 |
| 1992 Q1 |
-1.75 |
| 1992 Q2 |
-2.02 |
| 1992 Q3 |
-2.5 |
| 1992 Q4 |
-3.99 |
| 1993 Q1 |
-5.14 |
| 1993 Q2 |
-5.12 |
| 1993 Q3 |
-5.48 |
| 1993 Q4 |
-5.32 |
| 1994 Q1 |
-4.03 |
| 1994 Q2 |
-4.75 |
| 1994 Q3 |
-4.86 |
| 1994 Q4 |
-4.94 |
| 1995 Q1 |
-4.32 |
| 1995 Q2 |
-1.6 |
| 1995 Q3 |
0.98 |
| 1995 Q4 |
2.85 |
| 1996 Q1 |
2.79 |
| 1996 Q2 |
1.66 |
| 1996 Q3 |
-0.48 |
| 1996 Q4 |
-0.49 |
| 1997 Q1 |
0.07 |
| 1997 Q2 |
1.11 |
| 1997 Q3 |
3.18 |
| 1997 Q4 |
4.24 |
| 1998 Q1 |
5.88 |
| 1998 Q2 |
6.94 |
| 1998 Q3 |
8.51 |
| 1998 Q4 |
8.76 |
| 1999 Q1 |
8.66 |
| 1999 Q2 |
10.09 |
| 1999 Q3 |
9.91 |
| 1999 Q4 |
9.8 |
|
| Qtr |
% |
| 2000 Q1 |
12.21 |
| 2000 Q2 |
11.06 |
| 2000 Q3 |
11.46 |
| 2000 Q4 |
11.45 |
| 2001 Q1 |
9.53 |
| 2001 Q2 |
10.09 |
| 2001 Q3 |
9.43 |
| 2001 Q4 |
9.33 |
| 2002 Q1 |
10.6 |
| 2002 Q2 |
12.4 |
| 2002 Q3 |
13.82 |
| 2002 Q4 |
15.35 |
| 2003 Q1 |
14.73 |
| 2003 Q2 |
13.09 |
| 2003 Q3 |
13.05 |
| 2003 Q4 |
18.31 |
| 2004 Q1 |
19.55 |
| 2004 Q2 |
23.63 |
| 2004 Q3 |
32.73 |
| 2004 Q4 |
25.88 |
| 2005 Q1 |
25.12 |
| 2005 Q2 |
22.65 |
| 2005 Q3 |
15.15 |
| 2005 Q4 |
17.52 |
| 2006 Q1 |
16.82 |
| 2006 Q2 |
13.43 |
| 2006 Q3 |
8.11 |
| 2006 Q4 |
2.66 |
| 2007 Q1 |
-2.08 |
|