No individual or group hospital or medical service plan contract and no mutual benefit society offering individual or group hospital or medical service plan contracts issued or renewed in this State shall require an individual, as a condition of enrollment or continued enrollment under the plan contract, to pay a premium or contribution based on the individual’s gender that is greater than the premium or contribution for a similarly situated individual of the opposite gender who is covered under the same plan contract or a substantially similar plan contract offered by the same mutual benefit society.