Struck thru happen in a dirty factory where air quality is poor and some lint falls on a coin before it is struck. 1989 LD, 1990 SD, 1991 SD, 1992 SD, 1993 SD... In general, most shenyang mint coins have the issue, despite the coins being proof quality. Many coins are struck thru, but most submitters don't ask for it to be designated because it costs extra.