Not every achievement comes with a tidy percentage, and that's fine. You can write strong, credible bullets without inventing metrics.

Show the before and after

Even without numbers, you can describe what changed: 'Introduced a checklist that reduced repeat errors' is evidence.

Use scope and frequency

'Handled the busiest desk', 'main point of contact for three teams', 'daily' - these give a sense of scale without false precision.

Name the outcome or recognition

Promotions, being asked to train others, taking on extra responsibility - these are achievements.

Never invent a figure

A made-up metric is worse than none; it falls apart at interview. If you don't know it, don't guess it.

Estimate honestly if you must

If you genuinely recall an approximate figure, 'around' is acceptable. Precision you can't defend is not.