The scale of the challenge UK broadcasters face in the streaming era has been thrown into stark relief by a new report, which estimates that 34 extra series of the BBC hit Bodyguard – or 14 more Love Islands – would have needed to air last year to make up for the drop in traditional TV viewing as audiences flock to rivals including Netflix, Amazon and YouTube.

The report, by the media regulator Ofcom, highlights the huge growth in popularity of streaming services in the UK. The number of subscribers to the three most popular - Netflix, Amazon and Sky’s Now TV - leapt by almost a quarter last year to 19.1m.

Nearly half (47%) of UK homes now have a subscription streaming service, a significant increase on the 39% that did in 2017, with many households paying for two or more.

The rapid shift in the nation’s viewing habits continues to erode the popularity of traditional TV viewing. The average Briton now watches three hours and 12 minutes of TV a day – a drop of 20 minutes in the last two years and almost an hour since 2010.

The UK’s public service broadcasters, the BBC, ITV, Channel 4 and Channel 5, still provide the nation’s water cooler moments. More than 12 million people tuned into the final episode of Line of Duty earlier this year, and 14 million watched the conclusion of Bodyguard last year, making it the most-watched drama of 2018.

Ofcom’s report, however, said: “A few popular drama and entertainment programmes are not enough on their own to stem the overall decline in broadcast TV viewing.”

ITV announced last month that it is to air two series of Love Island a year from 2019 in an effort to bolster its audiences and commercial revenues. The second “winter edition” will be shot in South Africa.

Love Island has proven a hit with younger audiences. It is the most popular TV show among 16- to 34-year-olds, who are switching off traditional linear television at the fastest rate.

Ofcom’s report shows that the amount of traditional TV watched by 16- to 24-year-olds has halved since 2010 from 169 mins a day to 85 minutes a day last year. The decline among 25- to 34-year-olds was 39%, from 199 minutes to 122 minutes.

The report shows that the main beneficiaries have been paid-for streaming services such as Netflix and YouTube’s free online video platform.

It found that 18- to 34-year-olds spent the most time on YouTube each day, followed by Netflix and then ITV, BBC1 with Amazon Prime Video rounding out the top five sources of viewing.

The report, entitled UK Becomes a Nation of Streamers, also found that the Silicon Valley providers have a paucity of UK content on their services. British public service broadcasters spent almost £2.6bn making 32,188 hours of original programming last year, compared with the 221 hours made available by the subscription video-on-demand services. Netflix and Amazon are estimated to spend just a few hundred million dollars of their combined $20bn (£16.4bn) annual global programming budgets in the UK.

“Public service broadcasters are still important in meeting viewers’ desire for UK content,” said Ofcom. “UK audiences want original, UK-produced and UK-specific programmes. The vast majority of subscription video-on-demand programmes are US-made productions, designed to play out in multiple countries.”

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Subscription video-on-demand services, primarily Netflix and Amazon, became the most popular form of pay-TV in the UK last year. Ofcom said the low-cost nature of the new streaming rivals, which offer subscriptions from less than £10 a month, compared with pay-TV packages costing as much as £100, has widened the gap markedly over the last year.

Subscriptions to traditional pay-TV services in the UK such as Sky, Virgin Media, BT and TalkTalk stand at 14.3m, down from 15.1m in last year’s report.

ITV and the BBC are attempting to break into the booming subscription video-on-demand market with the launch later this year of BritBox, which will be priced at £5.99 a month.