Count while variable is not changing, vba

In my vba code I have a table that consists of hundreds of lines. ie:

TRE12_DO

TRI12_DO

GRO12_DO

The first five chars will be different, but always contatain five letter. Those that are a like will appear after each other in the table. Like above

I want to create a txt file that puts out:

TRE12 = 3

TRI12 = 2

GRO12 = 3

I know how to print etc.. But I dont know which Loop i should use for counting...