{"year":1850,"perhouse":5.55}
{"year":1860,"perhouse":5.28}
{"year":1870,"perhouse":5.09}
{"year":1880,"perhouse":5.04}
{"year":1890,"perhouse":4.93}
{"year":1900,"perhouse":4.76}
{"year":1910,"perhouse":4.54}
{"year":1920,"perhouse":4.34}
{"year":1930,"perhouse":4.11}
{"year":1940,"perhouse":3.67}
{"year":1950,"perhouse":3.37}
{"year":1960,"perhouse":3.35}
{"year":1970,"perhouse":3.14}
{"year":1980,"perhouse":2.76}
{"year":1990,"perhouse":2.63}
{"year":2000,"perhouse":2.59}