by some year

[punkt]

If we say : by some year, like
"By 1951 over one million had died on th road."
what is that means? in 1951 one year? or including years before 1951?
Thank you.

[2006]

If we say : by some year, like
"By 1951 over one million had died on th road."
what is that means? in 1951 one year? no or including years before 1951 yes, and at least some of 1951
Thank you.

2006