I found this:
thewall-usa.com/information.asp
HOW MANY NAMES HAVE BEEN ADDED SINCE THE MEMORIAL WAS DEDICATED?
Nine groups of names have been added since the Memorial was dedicated. In group 1 (1983) there were 68 names added, group 2(1984) 15 names, group 3 (1986) 110 names, group 4 (2001) six names, group 5 (2002) three names, group 6 (2003) six names, group 7 (2004) ten names, group 8 (2005) four names, group 9 (2006) four names, group 10 (2007) three names.
The bulk of the names in the first group of 68 were Marines killed when their R&R flight crashed in Hong Kong. (This exception to the criteria was ordered by President Ronald Reagan.)
Those in the group of 110 were added when the geographic criteria were enlarged to include people killed (95 servicemen) outside the war zone while on or in support of direct combat missions and 15 servicemen who had subsequently died of wounds received in Vietnam.
The latest three names added in 2007, brought the number of names on the black granite Wall to 58,256.
ARE THERE ANY CIVILIANS LISTED ON THE WALL?
No, the Memorial is dedicated to the 2.7 million men and women in the U.S. military who served in the designated war zone.
HOW ARE THE NAMES ARRANGED ON THE WALL?
They are in chronological order, according to the date of casualty within each day, the names are alphabetized. For the dead, the date of casualty is the date they were wounded (received in combat) or injured (received in an accident); for the missing, the date they were reported to be missing. The list starts and ends at the vertex (apex), beginning at the date 1959 (with first two names listed from the date of July 8, 1959) and the inscription (IN HONOR OF THE MEN AND WOMEN OF THE ARMED FORCES OF THE UNITED STATES WHO SERVED IN THE VIETNAM WAR. THE NAMES OF THOSE WHO GAVE THEIR LIVES AND OF THOSE WHO REMAIN MISSING ARE INSCRIBED IN THE ORDER THEY WERE TAKEN FROM US.) on panel 1E and going out to the end of the East wall, appearing to recede into the earth (numbered 70E - May 25, 1968), then resuming at the end of the West wall, as the wall emerges from the earth (numbered 70W - continuing May 25, 1968) and ending with the date of 1975 and its inscription (OUR NATION HONORS THE COURAGE, SACRIFICE AND DEVOTION TO DUTY AND COUNTRY OF ITS VIETNAM VETERANS. THIS MEMORIAL WAS BUILT WITH PRIVATE CONTRIBUTIONS FROM THE AMERICAN PEOPLE. NOVEMBER 11, 1982) at the bottom of 1W (last 18 names listed are from May 15, 1975). Thus the war’s beginning and end meet; the war’s complete, coming full circle, yet broken by the earth that bounds the angle’s open side and contained within the earth itself. Although 1959 is marked as the beginning on Panel 1, East wall, a Captain (Army) Harry G. Cramer was killed 21 October 1957 during a training action. He is listed on line 78, panel 1, East wall, which was added approximately a year after the Memorial was dedicated.
CRITERIA FOR NAMES ON THE WALL
Early in the effort to establish the Vietnam Veterans Memorial it was determined by the veterans that the memorial would contain the permanent inscription of the names of all who died or who remain missing in the war. The inscription of the names was the sole mandatory criterion set by the Vietnam Veterans Memorial Fund (VVMF) for designs entered in the Vietnam Veterans Memorial Design Competition. The list of names came from casualty lists compiled by the Department of Defense (DOD).