我国奶牛头平年产奶量增长情况 3,500 3,000 2,500 2,000 ,500 ,000 500 0 小心求的求少我国奶牛头平年产奶量增长情况 0 500 1,000 1,500 2,000 2,500 3,000 3,500 1961 1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005