This limitation is really is a bug. We build projects linked to many events in the past. For example, the development of the DDG-51 program has been ongoing since June of 1981, and will continue until at least 2022. Millions of dollars have been spent every year since 1981 and we have analytical reasons to track the timing of events and expenditures since then, connecting them logically and analytically to the future as models for current and future programs.
This is a place where if Microsoft can or will not correct this deficiency, a 3rd party should.