In an audit conducted between April 8 and April 14, average on-shelf-availability at Tesco, Asda, Sainsbury, Morrisons and Waitrose was 97.8%, compared with 96% for the same period in April 2009.
The best-performing category was dry goods, with 98.1% availability, followed by fresh food at 98.1% and beers, wines and spirits at 98%. The worst performers were bakery at 96.9% and frozen food at 96.3%.
Products with 100% availability included Nescafe Gold Blend, Jacobs Cream Crackers, Kellogg's Cornflakes and After Eight mints.
Thursday was the best day of the week for fully-stocked shelves.
The survey is conducted six times a year by Logobrand on behalf of ECR UK, and tracks availability across 200 branded and own-label products in 160 Sainsbury, Waitrose, Tesco, Morrisons and Asda stores.
The products are top-selling lines and were designed to be representative of an average family shop, said a spokesman.
By completing audits on different days of the week, at different times of day and in different parts of the country, the survey was also able to "reflect differences within the full trading period and area", he added.
The checks are carried out by trained auditors, who record if a product is on sale and, where it is unavailable, whether there is an 'out of stock' label at the shelf-edge.
How manufacturers use the data
Nestlé UK uses the results from the survey "extensively", said a spokesman. "In the first instance, our customer-specific supply chain managers analyse the data and work with their retail counterparts to fix specific availability issues.
"At a more senior level, the survey results form a key part of the monthly supply chain leadership team meeting chaired by Nestlé's supply chain director, which provides an additional forum for issue resolution as well as celebrating successes."
It added: "Within the customer-facing commercial teams, the survey is used to validate our view of customer-specific availability and is a key feed into the flexible way we deploy our field sales resources."
For the latest survey results, click here