A senior PSNI officer has said victims of paramilitary-style attacks need to co-operate more with police to bring those responsible to justice.
Detective Chief Superintendent Raymond Murray said he couldn't recall a single instance when a victim gave evidence to those investigating a shooting or assault by republican and loyalist thugs.
In many cases officers know who is responsible, but lack the testimony to make arrests and bring prosecutions.
Police statistics show there were 71 victims of paramilitary-style assaults and shootings in the 12 months up to December 2018 - more than one a week.
Yet in the vast majority of cases no arrests were made and no one made amenable.
Arrests for paramilitary activity fall under Section 41 of the Terrorism Act 2000.
In the 12-month period, 164 arrests were made for all terrorist activity, with 11 people subsequently charged.
Mr Murray said a lack of evidence means few of the perpetrators of the violence are ever brought to court.
He added that victims need to speak out more to help address the problem.
"It is the difference between knowing and proving," he explained.
"By and large we will find out who is doing it, but what we will have is a victim who will not co-operate.
"I cannot remember one victim who co-operated with us, whether that is through fear or because they have their own issues to hide, but they don't co-operate.
"We do not get witnesses co-operating in these type of offences as well.
"The paramilitaries have been doing this for a long time, they pick their time, their place and they are resistant to reactive investigation, and we know that.
"We don't shy away from the problem but we have to prove beyond reasonable doubt, so one person saying 'such and such did this' isn't enough if they are not prepared to go into the witness box."
PSNI statistics show there were 20 casualties of paramilitary-style shootings during the 12 months up to December 2018, compared to 26 during the previous 12 months.
And there were a further 51 casualties of paramilitary-style assaults in the 12 months to December 2018, down from 75 in the previous year.
The most recent figures include three paramilitary-style shootings in Londonderry during November.
The number of shootings in Derry over the year increased from six to seven, while incidents elsewhere have fallen.
Mr Murray said the figure for Derry was disappointing, and he claimed it could lead to the city missing out on potential investment.
He added: "For six or seven months there had been no paramilitary shootings in the city and we thought that was a positive step forward for the community and the image of the city.
"We want Derry/Londonderry to do well, we want it to be prosperous, we want it to be one of the top tourist destinations in Europe.
"But these people doing this is the key reason the city is being held back.
"Instead of people getting opportunities, this type of crime really impacts far more than people realise. People are not going to invest in an area where this type of activity goes on, it is locking people into social deprivation."
The number of assaults carried out by paramilitaries varies greatly between republican and loyalist groups. In the 2017/18 financial year, loyalists were behind 50 assaults while republicans were blamed for 15. Republicans were behind 21 shootings, and loyalists one in the same period.
Mr Murray added: "There does seem to be a culture within republicanism about the use of the gun, but there are no hard and fast rules. Some loyalists will use firearms, others use bats or whatever comes to hand, but if there is a loyalist outfit in east Belfast that want to take a gun out, they could.
"But there does seem to be more of an ethos amongst republicans to bring guns out.
"We don't know why loyalism tends to look towards the bat and republicanism tends to look towards the gun, but that seems to be the case and it is borne out year after year.
"But it doesn't matter whether it is a gun or a bat - what they are doing is traumatising communities."
He also dismissed any perception that paramilitary organisations offer protection to their respective communities.
He said: "Let us be quite clear on this: paramilitary organisations who say the community is asking them to do what they do is not right.
"The first reason they are doing this is because they have criminal business interests, and the second thing it is about is personal grudges.
"But it is largely about controlling their community, not about protecting them.
"The biggest hypocrites of all are those who shoot drug dealers, trumpet about shooting drug dealers, tell people they are protecting the community and then collect their money from the drug dealers so they can continue to peddle their drugs."
The rise in paramilitary attacks in Derry while other areas have seen an decrease has been attributed by some to a loss of funding for the Time 2 Choose project based in the city.
This was operated by the Rosemount Resource Centre (RRC), the sole mediation centre accepted by paramilitaries.
Tommy McCourt from RRC said the number of calls about or from people under threat is more than it can deal with.
He said: "We are getting on average four complaints a day and we are just not able to handle all of them.
"We had seven support workers attached to the Time 2 Choose project who all shared the load of mediating with the paramilitaries, providing training and counselling around options to the people under threat.
"Now that workload is being done on a voluntary basis by a couple of people, but it is simply far greater than we can cope with.
This means there are people under threat that we don't hear about until we see in the media that someone has been shot.
"We are still able to prevent a situation developing that far in a lot of cases.
"And, if it wasn't for our volunteers, the situation in Derry would be a lot worse."