Deleting multiple rows with duplicate values in one column

I have about 10,000 rows of information that look like this:

Reference Date Trans Description Segment 1 Segment 2
JE 373 3/31/13 Record deferred revenue 1030 3203
JE 373 3/31/13 Record deferred revenue 1030 3203
JE 373 3/31/13 Record deferred revenue 1030 3203
JE 373 3/31/13 Record deferred revenue 1030 3203
JE 373 3/31/13 Record deferred revenue 1030 3204
JE 373 3/31/13 Record deferred revenue 1030 3204
JE 373 3/31/13 Record deferred revenue 1030 3204
JE 373 3/31/13 Record deferred revenue 1030 3205
JE 373 3/31/13 Record deferred revenue 1030 3205
JE 373 3/31/13 Record deferred revenue 1030 3205
JE 373 3/31/13 Record deferred revenue 1030 3205


and so forth, with the fifth column's (segment 2) values changing every 100 or so lines. Want to delete all the excess rows with duplicate information, but keep just one row with each of column 5's numbers. So hypothetically, I would want it to look like:


Reference Date Trans Description Segment 1 Segment 2
JE 373 3/31/13 Record deferred revenue 1030 3203
JE 373 3/31/13 Record deferred revenue 1030 3204
JE 373 3/31/13 Record deferred revenue 1030 3205
JE 373 3/31/13 Record deferred revenue 1030 3206
JE 373 3/31/13 Record deferred revenue 1030 3207

etc...


Is there a fast way to do this so I don't have to scroll through 10,000 lines of text?

Many thanks!