The extent indicator is a calculation of the net (non-overlapping) extent of protected areas using mean high water as the boundary between the at-sea and on-land measures. The indicator was expanded in 2014 to include wider countryside designations. The extent of protected areas is assessed over time since 1950, in the marine and terrestrial environments. The site condition statistic covers the cumulative proportion of Areas of Special Scientific Interest (Northern Ireland) and Sites of Special Scientific Interest (England and Scotland) in ‘favourable’ or ‘unfavourable-recovering’ condition, over the last decade. These statistics are part of the UK Biodiversity Indicators.