“Net earned premiums” means the amount arrived at by:

1. (a) Deducting all return premiums, premiums on policies not taken, and premiums paid for reinsurance, from
2. (b) Gross premiums on ocean marine insurance contracts written during the current calendar year, to which remainder is added
3. (c) Unearned premiums on outstanding ocean marine business at the end of the preceding calendar year, and from which sum is deducted
4. (d) Unearned premiums on outstanding ocean marine business at the end of the current calendar year.