Dear Stata Users

I have a string variable yearmonth: for Jan 2004 it's stored as "200401". I need to convert it to a readable year/month format. I have used the following code:

Code:
generate month = date( yearmonth ,"YM")
format %tm month
The code above produces strange date variable.

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input str6 yearmonth
"200401"
"200402"
"200403"
"200404"
"200405"
"200406"
"200407"
"200408"
"200409"
"200410"
"200411"
"200412"
end
How to alter a code to get a meaningful year/month variable?
Thank you.