It will take nearly two decades for the government to reach its own target for turning around the collapse in rape prosecutions in England and Wales at the current pace of change, according to analysis.

In June the government promised to halt a collapse in the number of rapists being brought to justice, and vowed to return the number of charges and prosecutions to 2016 levels before the end of this parliament.

But new quarterly Crown Prosecution Service data shows that in the last 12 months just 41 extra suspects were charged compared with the year before. In 2015-16 the CPS charged 3,910 suspects with rape, but in the year ending June 2021, 1,972 charges were made.

Guardian analysis, based on the number of charges brought in the past 11 quarters modelled on to future quarters, shows it would take 18 years at the current pace to get back to that figure.

Dame Vera Baird, the victims’ commissioner for England and Wales, said it was “hard to see even the green shoots of a recovery”. She added: “Presently, the government’s stated ambition feels more like a pipe dream and victims will continue to be failed unless the CPS rapidly and urgently ups the ante.”

It comes as pressure mounts on the government to take decisive action to tackle violence against women and girls, after the murders of Bibaa Henry, Nicole Smallman and Sarah Everard and the death of Sabina Nessa, and a 70% fall in rape prosecutions since 2016-17.

Campaigners said the government’s target increasingly looked “wholly unrealistic” and called for urgent action. Last month the prime minister, Boris Johnson, said he could not guarantee that targets to improve rape prosecution and conviction rates set out in the government’s rape review would be met.

“The figures are incredibly worrying, because despite promises of improvements in prosecution volumes that would take us closer to 2016 levels, we’re instead seeing that the criminal justice system still fails women,” said Andrea Simon, the director of the End Violence Against Women coalition. “These figures must be a wake up to government, the CPS and police forces that we need urgent change in the justice system response to violence against women.”

The figures, covering the three-month period from 1 April to 30 June 2021, also show rape complainants continue to face long – and increasing – waits for cases to come to trial. The average time from when police refer a case to the CPS to a charge has increased from 155.1 days in January to March 2021 to 170.2 days in April to June – four times as long as the average across all crimes.

“For victims and survivors to wait for so long just to hear whether their perpetrator will be charged is extremely difficult and will have a detrimental effect on their wellbeing and their ability to engage with the criminal justice process,” said Jayne Butler, the chief executive of Rape Crisis. “The timescales for rape cases will discourage victims and survivors from seeking justice: this must change.”

The number of prosecutions and convictions increased in the last quarter, as recovery from the pandemic continues. There were 601 completed prosecutions in the last quarter, almost double the number of the preceding quarter. Convictions increased from 223 to 398 in the same period.

Campaigners also warned that victims of domestic abuse were being failed. The new data shows the number of suspects charged dropped by 7% from 11,709 in January to March to 10,840 between April and June, the number of completed prosecutions fell from 14,695 to 13,938 and the number of convictions fell from 12,363 to 10,607.

The shadow solicitor general, Ellie Reeves, said the government continued to fail rape victims. “Rape conviction rates have plummeted, victims are being deserted and it is clear this is a government that has absolutely no desire to fix the mess it has created, nor a plan to keep women and girls safe,” she said.

The justice secretary, Dominic Raab, and the attorney general, Suella Braverman, said: “Our track record to date is not good enough and this data is a clear demonstration of why we must galvanise all aspects of the criminal justice system – from the police station to the court room – to improve outcomes for victims. Everyone will be held accountable for the successful delivery of the rape action plan.”