Answer: There are a few reasons you might see a decrease. One is that voles or squirrels might be stealing the bulbs. Another reason might be that the bulbs have divided and become crowded and are too weak to bloom as a result. If this is happening you will see more bulbs with smaller foliage developing at the site where there used to be just one bulb. Another possibility is that over time the bulbs are losing vigor. This can be due to the area becoming more shaded by nearby trees growing bigger, or to foliage being removed before it is fully ripened, or to lack of fertility, or to dry spring weather limiting the foliage development. I hope this helps you trouble shoot.
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