Read this and answer the question. If the question is unanswerable, say "unanswerable".

Typical American families did not fare as well, nor did those "wealthy-but-not wealthiest" families just beneath the pyramid's top. On the other hand, half of the poorest families did not have wealth declines at all during the crisis. The Federal Reserve surveyed 4,000 households between 2007 and 2009, and found that the total wealth of 63 percent of all Americans declined in that period. 77 percent of the richest families had a decrease in total wealth, while only 50 percent of those on the bottom of the pyramid suffered a decrease.

How many of the poorest families did not have any wealth decline during the financial crisis?
half