Excel - count unique value in a text column but do not count blank cells

I have a column which has duplicate values and some cells are blank cells.

The following works as long as I have data entered into every cell:

=SUM(IF(FREQUENCY(MATCH(I3:I70,I3:I70,0),MATCH(I3: I70,I3:I70,0))>0,1))

But if I have any blank cells in the data range then I am given a #N/A error message.

Please advise what I need to do.

Example - the following show 17 cells (including 3 blank cells).
If I use the above formula to give me the number of unique data, my answer should be 5 (groups of the same data). Unfortunately the above formula does not work when there are blank cells as I get a #N/A error. What do I need to do the fix the formula?

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thanks heaps

I found the answer to this question on You TUBE

Excel Magic Trick # 272: Count Unique Or Duplicate Records - YouTube

=SUMPRODUCT(('YWLP DATA 2011-2012'!I3:I70<>"")*(1/COUNTIF('YWLP DATA 2011-2012'!I3:I70,'YWLP DATA 2011-2012'!I3:I70&"")))