1999-08←  1999-09 looping  →1999-10

19990902_0000 UTC	19990903_0000 UTC
19990904_0000 UTC	19990905_0000 UTC
19990906_0000 UTC	19990907_0000 UTC
19990908_0000 UTC	19990909_0000 UTC
19990910_0000 UTC	19990911_0000 UTC
19990912_0000 UTC	19990913_0000 UTC