The number of kidnappings in Colombia has almost halved in the first half of the year, the government says.
Many of the kidnappings were carried out by Farc rebels
It says 966 people were abducted in the first six months of 2004, compared with 1,906 in the same period last year.
A study by the Department of National Planning also estimates kidnapping has cost Colombian society some $260m over the past eight years.
An average of 3,000 people were kidnapped each year between 1996 and 2003, totalling 21,000, it adds.
Most were taken hostage for ransom.
An estimated $57m in ransom money was paid out in the eight-year period, the AP news agency reported.
The majority of the victims spent an average of one month in captivity and their release was secured with a $20,000 ransom.
The researchers estimated that the cost to the Colombian economy was $150m, including loss of income.
The government has also spent $110m on intelligence, training and equipment in a bid to crack down on abductions.
Most of the kidnappings were carried out by Colombia's two main left-wing rebel groups, the Farc and the ELN, which have waged a 40-year conflict against the Colombian state.