Sex offence conviction rates 'low'
Only a fraction of sexual offences in England and Wales results in a conviction, a statistical review says.
It said there were up to 517,000 sex assault claims every year, with 54,310 sex offences recorded as crimes by police and 5,620 offenders convicted.
Statisticians analysing this data said the proportion of sex crimes leading to conviction was "small".
Justice Minister Jeremy Wright said that all sexual offences were "abhorrent".
The Office for National Statistics, the Home Office and the Ministry of Justice carried out the review.
Those compiling it said a precise percentage figure for the data could not be calculated because the figures were not directly comparable.
The review also said one in five females said they had been the victim of a sexual offence since the age of 16.
When sex offences were reported to police they were more likely to be solved than other crimes, the review found.Case length
The sanction detection rate for sex offences was 30%, compared to 27% for all crimes recorded by police in 2011-12.
A sanction detection is where a person is either charged, cautioned, issued with a summons, given a reprimand or final warning, or the offence is admitted and taken into consideration by the courts, or a fixed penalty notice is issued.
However, the detection rate was lower than for other violent crimes.
Researchers also found that 1,500 sex offenders were cautioned in 2011, including 19 people who were cautioned for rape.
However, the "rape caution" numbers were almost half the number of the previous year - and of the 19 cautions, 16 were issued to offenders under 18.
And the study found that it took almost 500 days to complete a case, from the moment a sex offence occurred to when it was resolved.
Mr Wright said: "Very tough sentences are available to the courts for those who commit the most serious offences including a new mandatory life sentence which we have introduced for anyone convicted of a second very serious sexual or violent crime.
"We are already looking into how police cautions are being used. We shouldn't remove the right for police officers to exercise discretion but the public are right to expect that people who commit serious crimes will be brought before a court."