Which year had the most synths/samplers produced?

[gs]

The way the question is worded leaves too much to interpretation. If we're talking specifically about synths and samplers (which were still fairly distinctly separate concepts back in the mid 80s), then I'd go with 85/86 as the period of most units produced. Remember that this was the period that Korg did really well with the DW series and Ensoniq had come into the picture with their samplers and waveform synths.

However, if we're talking about the period 89-91, then I'd say that the ROMpler market was producing far more units per year than both synth and samplers from the 85-86 period. It was during the 89-91 period that the difference between synths and samplers became lost on the general public, who looked at them as keyboard instruments that produced a sound you wanted by pressing a button - a simple concept to grasp, which translated into healthy sales in the amateur hobbyist-musician market.