Complex sentence: In 1801,396 people lived in 43 houses, which gives an average occupancy of 9.2 people, which had increased to 9.8 in 1811, when 450 people occupied 46 houses.
Split into simpler sentences: In 1801,396 people lived in 43 houses, which gives an average occupancy of 9.2 people. This had increased to 9.8 in 1811, when 450 people occupied 46 houses.