The number of pending home sales in the United States was at its highest point in more than a decade in April, according to the National Association of Realtors.

The organization issues a monthly update of its Pending Home Sales Index, which measures transactions where a contract has been signed but the sale has not been finalized. The transaction is typically closed within one or two months of the contract signing.

When the Pending Home Sales Index stands at 100, it indicates that pending contract activity is equal to that observed in the year 2001. There were between 5 million and 5.5 million home sales in that year, which the National Association of Realtors says is normal for the current U.S. population.

In April, the Pending Home Sales Index reached 116.3. This figure was up 5.1 percent from the upwardly revised index of 110.7 in March and 4.6 percent from the April 2015 figure of 111.2. April marks the third consecutive month where pending sales activity has increased and the 20th month in a row where activity was higher than the same month in the previous year.

Pending sales were up in all four geographic regions stipulated by the National Association of Realtors except the Midwest, which had a slight decline. Lawrence Yun, chief economist at the National Association of Realtors, says large gains in the South and West brought the Pending Home Sales Index to its highest point since February 2006, when it stood at 117.4.

"The ability to sign a contract on a home is slightly exceeding expectations this spring, even with the affordability stresses and inventory squeezes affecting buyers in a number of markets," he said. "The building momentum from the over 14 million jobs created since 2010 and the prospect of facing higher rents and mortgage rates down the road appear to be bringing more interested buyers into the market."

The Northeast was the only region where pending sales were below the 2001 level, with the Pending Home Sales Index standing at 98.2 for April. However, the region had the largest year-over-year gain, with activity up 10.1 percent from April 2015 and 1.2 percent from March.

The West had the largest gain from March, with the region's index rising 11.4 percent from that month and 2.8 percent from the previous year to 106.2. The South had the highest index, 133.9, which was up 6.8 percent from March and 5.1 percent from April 2015. In the Midwest, the Pending Home Sales Index dropped 0.6 percent to 112.9, but this figure was 2 percent higher than the previous year.

Yun says that while recent buyers have often faced low inventories and elevated prices when looking for a home, they are continuing to benefit from low mortgage rates. The average commitment rate for a 30-year fixed rate conventional mortgage has stayed below 4 percent in all but one of the past 17 months, according to Freddie Mac. Yun expects rates to stay low in the coming months, but says they could increase suddenly if they are pushed up by inflation.

"Even if rates rise soon, sales have legs for further expansion this summer if housing supply increases enough to give buyers an adequate number of affordable choices during their search," said Yun.

The National Association of Realtors determined that the annual pace of existing home sales in the first quarter of 2016 was 5.66 million, the best performance since 2007. Yun expects that existing home sales for the year will total approximately 5.41 million, a 3 percent increase from 2015. He also forecasts that year-over-year home price appreciation will come down from last year's average of 6.8 percent and reach a point of 4 to 5 percent.