Key	Year	Country	Total number of dairy cows	Total number of dairy herds	Average of cows per herd	Average milk production per cow per year (kg)	Percent of fat production per cow per year (%)	Percent of protein production per cow per year (%)	Others	E-mail address of the responsible
16	Average during 2009	USA	9,201,000	54,942		9,353 kg/yr	3.67		USDA-NASS	melvin.tooker@ars.usda.gov
15	Average during 2008	USA	9,315,000	57,127 licensed dairies		9,271 kg/yr	3.68		USDA-NASS	inquiry@aipl.arsusda.gov
14	Average during 2007	USA	9,158,000	59,135 licensed dairies		9,193 kg/yr	3.68		USDA-NASS	inquiry@aipl.arsusda.gov
13	Average during 2006	USA	9,112,000	61,990 licensed dairies		9,050 kg/yr	3.69		USDA-NASS	inquiry@aipl.arsusda.gov
12	Average during 2005	USA	9,043,000	64,555 licensed dairies		8,875 kg/yr	3.66		USDA - NASS	inquiry@aipl.arsusda.gov
9	Average during 2003	USA	9 084 000	70 410 licensed dairies		8 504 kg/yr	3.67		USDA - NASS	rlaipl@aipl.arsusda.gov
10	Average during 2002	USA	9 139 000	74 110 licensed dairies		8 440 kg/yr	3.68		USDA - NASS	rlaipl@aipl.arsusda.gov
7	Average during 2001	USA	9 103 000			8.238 kg/yr	3.67		USDA - NASS	rlaipl@aipl.arsusda.gov
11	Average during 2004	USA	9 012 000	66 825 licensed dairies		8 599 kg/yr	3.69		USDA - NASS	rlaipl@aipl.arsusda.gov