Crimes recorded by police in Wales fell by 9% in the 12 months to June this year.
Overall crimes dropped to 215,076 crimes over the year, according to the latest Home Office figures.
There were big falls in robbery, car crime and criminal damage but a slight rise of 1% in sexual offences.
The Welsh force with the biggest fall in recorded crime was South Wales Police, which dropped 13.3% to the same level as 25 years ago.
It was followed by Dyfed-Powys (down 9%), North Wales (down 6%), while Gwent's figures remained static (0%).
South Wales Police said their figures had not been as low since 1985 and equated to 42 less victims of crime per day.
This places the force as the ninth most improved in Wales and England for reducing crime and the most improved force for reducing sexual offences.
The figures show that there were 15,409 fewer victims of crime overall and detection rates for crime were up to 30.9%.
Deputy Chief Constable Colette Paul said:"Our staff should take great pride in knowing that they have helped to bring crime in south Wales down to its lowest level since 1985.
"The figures out today evidence the determined attitudes of our staff to make a difference to life in south Wales, and although we're facing challenging times, we will strive to maintain these excellent performance levels so our communities continue to get a policing service they can rely on."
Two forces (Dyfed- Powys and Gwent) saw a 15% rise in sexual offences over the period.
Senior officers believe the increase in sexual offences is mainly because victims have more confidence to report what has happened to them and police are more consistent in the way they record the crimes.
Gwent Police's temporary Assistant Chief Constable Simon Prince said: "Sexual offences is an area of crime which is historically under-reported across the UK.
"Our forcewide publicity campaigns coupled with the establishment of the Onyx Unit, a dedicated team which investigates sexual crime and offers specialist support to victims, have encouraged more people to have the confidence to come forward to report sexual offences to the police."
He added that the overall figures for Gwent showed crime was falling - from more than 60,000 crimes per year in 2005, to below 50,000 crimes this year.
Burglary in Gwent was also up 21%, and ACC Prince said the force had conducted a number of targeted operations and the trend was in the process of being reversed.
He added: "This is an area that we will continue to focus on both with enforcement activity but also working with our partners to reduce offending behaviour."
Dyfed-Powys Police recorded the lowest anti-social behaviour levels in the whole of England and Wales, according to the British Crime Survey, which runs parallel to the official Home Office statistics.
Deputy Chief Constable Jackie Roberts said: "What is also important to remember is that these reductions come in an area with the lowest crime rates in the country and at a time when everybody was starting to feel the true impact of the economic downturn.
"Our force has consistently delivered a high quality policing service to the public across the Dyfed Powys area and the excellent performance outlined above is testament to that.
"We are now looking at the details behind the chancellor's announcement yesterday to see what they mean for the force in cash terms."
North Wales Police Deputy Chief Constable, Ian Shannon said: "We are very pleased that crime has fallen over the last 12 months by 6% and are more encouraged as the reduction has accelerated since March (a 10.4% fall from April - September 2010 compared with 2009) with a particularly sharp fall in violent crime."