i Register
In some senses, dwindle is marked as figuratively. Watch for register when choosing this word.
ADV
fast, quickly, rapidly
The number of students interested in learning Latin has dwindled rapidly over the past decade.
gradually, slowly | steadily
away
His savings slowly dwindled away until he had almost nothing left.
PREP
to
The number of students in the evening class gradually dwindled to just five by the end of term.