Another load, I'm afraid.
We'll leave aside that 1961-1965 is five years.
In 1961, we had a grand total of 3,205 military advisors in Vietnam. We lost 16 people.
1962: 11,300 with 52 killed.
1963: 16,300 with 118 killed.
1964: 23,300 with 206 killed.
1965: 184,300 with 1,863 killed.
1965 is when the first combat troops actually arrived (the 9th Marine Expeditionary Brigade) and it was the first year that the number of people in Vietnam actually became comparable to the number of troops in Iraq. In 1965 alone, the casualty count in Vietnam was almost as great as the whole Iraq war so far.
The numbers for 1971 and 1972 don't quite match those in your reference either. 1971 alone resulted in 2,357 dead.