the population. During the English Civil War Norfolk was largely Parliamentarian. The economy and agriculture of the region declined somewhat. During the Industrial Revolution Norfolk developed little industry, except in Norwich which was a late addition to the railway network. Early military units included the Norfolk Militia. In the 20th century the county developed a role in aviation. The first development in airfields came with the First World War; there was then a massive expansion during the Second World War with the growth of the Royal Air Force and the influx of the American USAAF 8th Air Force which operated from many Norfolk airfields. The local British Army regiments included the Royal Norfolk Regiment (now the Royal Anglian Regiment) and the Norfolk Yeomanry. During the Second World War agriculture rapidly intensified, and it has remained very intensive since, with the establishment of large fields for growing cereals and oilseed rape. Economy and industry In 1998 Norfolk had a Gross Domestic Product of £9,319 million, which represents 1.5% of England's economy and 1.25% of the United Kingdom's economy. The GDP per head was £11,825, compared to £13,635 for East Anglia, £12,845 for England and £12,438 for the United Kingdom. In 1999–2000 the county had an unemployment rate of 5.6%, compared to 5.8% for England and 6.0% for the UK. Data from 2017 provided a useful update on the county's economy. The median hourly gross pay was £12.17 and the median weekly pay was £496.80; on a per year basis, the median gross income was £25,458. The employment rate among persons aged 16 to 64 was 74.2% while the unemployment rate was 4.6%. The Norfolk economy was "treading water with manufacturing sales and recruitment remaining static in the first quarter of the year" according to research published in April 2018. A spokesperson for the Norfolk Chamber of Commerce made this comment: "At a time when Norfolk firms face steep up-front costs, the apprenticeship system is in crisis, roads are being allowed to crumble, mobile phone and broadband 'not-spots' are multiplying, it's obvious that the key to improved productivity and competitiveness lies in getting the basics right". The solution was seen as a need for the UK government to provide "a far stronger domestic economic agenda ... to fix the fundamentals needed for business to thrive here..." In 2017, tourism was adding £3.25 billion to the economy per year and supported some 65,000