Recorded crimes have fallen for a second consecutive year, but more people are coming forward to report sexual assaults.
Official police figures show 20,289 fewer offences were reported in 2011 compared with 2010.
A total of 406,056 crimes were reported last year - the lowest figure in 15 years.
Sexual assaults rose by about 15%, with about 450 more people going to police in 2011.
Reports of crimes classed as dangerous activity that endangers the community rose 14%, with 120 more cases reported last year.
The number of murders fell from 46 in 2010 to 39 last year, while theft was down by about 1500 cases.
Assaults fell 5% to 2237 offences, while illegal drug cases dropped about 10% to 20,000, led by a fall in cannabis offences.
Property damage and environmental pollution offences fell 11%, while harassment and abduction cases fell 8.5%.
Robbery and extortion offences fell more than 7%.
Crime in Canterbury fell by about 22%, while Auckland City (up 8.3%) and Waikato (up 1.7%) were the only two regions to record increases. Crime in Southland fell about 13% and Northland dropped 10.5%.
Deputy Police Commissioner Mike Bush says while they are pleased reported crime is dropping, there is still a way to go. Officers will continue targeting areas that need attention including vehicle thefts and burglaries.
Mr Bush says police have campaigned to make people feel more comfortable about reporting sexual crimes and does not believe the actual incidence of sexual crimes has increased.
Police say for the first time in a decade, family violence is levelling off. Mr Bush says police and other agencies have run similar campaigns to encourage the reporting of this type of violence.
Official figures on this will be released in the middle of the year.
Quakes affect crime rate
Police in Canterbury say the 22% drop in crime reflects the impact of the region's earthquakes.
District commander Superintendent Gary Knowles says they have established neighbourhood policing teams but residents have also shown a greater willingness to report crime.
Mr Knowles says the central city was traditionally a prominent location for alcohol and disorder offences, but since it is now closed following the devastating February quake that has contributed to a drop in crime of 41% in the area.
Auckland crime up during Rugby World Cup
The Rugby World Cup created a spike in crime figures for Auckland City.
Police say public order offences increased by just over 15% due largely to liquor ban breaches. Nearly 1000 more of these offences were recorded in 2011 than in the previous year.
Police say half of the increase happened during the New Zealand-hosted tournament in September and October. There were also more officers in the city actively enforcing various liquor bans.