I have about 100 worksheets and I want to combine them into one. All the first rows should be together and so as all the second rows etc.
For example,

sheet1
a a a
b b b
c c c

sheet2
aa aa aa
bb bb bb
cc cc cc

The result is:

sheet3
a a a
aa aa aa
b b b
bb bb bb
c c c
cc cc cc