Great Britain contained about 10.8 million people in 1801, 20.7 million in 1851 and 37.1 million by 1901. This corresponds to an annual population growth rate of 1.3% in 1801-1851 and 1.2% in 1851–1901, twice the rate of agricultural output growth. In addition to land for cultivation there was also a demand for pasture land to support more livestock. The growth of arable acreage slowed from the 1830s and went into reverse from the 1870s in the face of cheaper grain imports, and wheat acreage nearly halved from 1870 to 1900.