Ebel rough age determination by year of manufacture of chronographs

The year of manufacture of the following chronographs allows at least a rough age determination based on model and year of manufacture:

1988 Ref. 1205/1134901, Cal. 134, 17 jewels, stainless steel, date, automatic

1989 Kal 134, 18K gold, date, automatic

1993 Zenith Cal. 400, 31 jewels, automatic, perpetual calendar and moon phase, 18k yellow gold

1994 Zenith cal 400, 31 jewels, automatic, date, no perpetual calendar

1981 - 1989 El Primero cal. 400, date, automatic, steel/gold

Source: Wolfgang Salm "Wristwatches"