The average balance of 401(k) retirement plan accounts managed by Fidelity Investments rose to $74,900 at the end of the first quarter, the highest level since the company began tracking balances in 1998.

When breaking the numbers down further, Fidelity found that workers who have saved continuously with the same employer for at least 10 years have amassed an average balance of $191,000. For the 10-year continuous contributor aged 55 or older, the average balance has reached $233,000.