Key	Year	Country	Number of lactations	Length of the lactations (days)	Milk yield per recorded cow (kg)	Milk per cow in 305 days (kg)	Percent fat content (%)	Percent protein content (%)	Calving interval (days)	Others	E-mail address of the responsible
13	Average during 2010	USA	4,349,798	305	10,218 kg/yr	10,218 kg/yr	3.67	3.09		DHI Herd Averages	aipl.inquiry@ars.usda.gov
12	Average during 2009	USA	4,469,906	305	10,125	10,125	3.69	3.09		DHI Herd Averages	melvin.tooker@ars.usda.gov
11	Average during 2008	USA	4,478,447	305	10,088 kg/yr	10.088 kg/yr	3.70	3.10		DHI Herd Averages	inquiry@aipl.arsusda.gov
10	Average during 2007	USA	4,338,693	305	10,049 kg/yr	10,049 kg/yr	3.69	3.09		DHI Herd Averages	inquiry@aipl.arsusda.gov
9	Average during 2006	USA	4,292,565	305	10,007 kg/yr	10,007 kg/yr	3.70	3.08		DHI Herd Averages	inquiry@aipl.arsusda.gov
8	Average during 2005	USA	4,214,003	305	9,913 kg/yr	9,913 kg/yr	3.68	3.07		DHI Herd Averages	inquiry@aipl.arsusda.gov
7	Average during 2004	USA	4 245 910	305	9,639 kg/yr	9,639 kg/yr	3.69	3.09		DHI Herd Averages	rlaipl@aipl.arsusda.gov
6	Average during 2003	USA	4 331 143	305	9 632 kg/yr	9 632 kg/yr	3.69	3.07		DHI Herd Averages	rlaipl@aipl.arsusda.gov
5	Average during 2002	USA	4 412 866	305	9 621 kg/yr	9 621 kg/yr	3.69	3.07		DHI Herd Averages	rlaipl@aipl.arsusda.gov
4	Average during 2001	USA	4 391 799	305	9 456 kg/yr	9 456 kg/yr	3.68	3.08		DHI Herd Averages	rlaipl@aipl.arsusda.gov