WASHINGTON (AP) — Fewer Americans signed contracts to buy previously occupied homes in December, suggesting a slowdown in real estate. Pending home sales fell to the lowest point since October 2011.The National Association of Realtors said its seasonally adjusted pending home sales index dropped 8.7 percent last month to 92.4. That’s the seventh straight monthly decline for the index, which previews upcoming sales. A one- to two-month lag usually exists between a signed contract and a completed sale.Rising mortgage rates and price increases crimped sales in recent months.