Group应该是保险公司排除烂人的方法，因为好像法律规定不能按照个人情况定价

Under the health care law, insurance companies can account for only 5 things when setting premiums.

• Age: Premiums can be up to 3 times higher for older people than for younger ones.

• Location: Where you live has a big effect on your premiums. Differences in competition, state and local rules, and cost of living account for this.

• Tobacco use: Insurers can charge tobacco users up to 50% more than those who don’t use tobacco.

• Individual vs. family enrollment: Insurers can charge more for a plan that also covers a spouse and/or dependents.

• Plan category: There are five plan categories – Bronze, Silver, Gold, Platinum, and Catastrophic. The categories are based on how you and the plan share costs. Bronze plans usually have lower monthly premiums and higher out-of-pocket costs when you get care. Platinum plans usually have the highest premiums and lowest out-of-pocket costs.

Factors that can’t affect premiums

• Insurance companies can’t charge women and men different prices for the same plan.

• They also can’t take your current health or medical history into account. All health plans must cover treatment for pre-existing conditions from the day coverage starts.

https://www.healthcare.gov/how-plans-set-your-premiums/