Postal officials said the policy would affect about 30 percent of the 400,000 parcels usually mailed daily in California.
If adopted nationwide, the rule would affect 77,000 buses, about 22 percent of those in use.
It is believed to affect about four percent of the population.
The income tax increase for people making more than $100,000 affected only about 5 percent of residents.
The two-hour ban affects about 80 percent of all domestic commercial flights.
The splitting, however, now affects about 30 percent of the bark coming down one side.
The cuts at the science and research center will affect about 13 percent of the center's 890 employees.
The condition affects about 5 percent of all women in their reproductive years.
With seven other states in the East following California's lead on air quality regulations, the plan could potentially affect about 30 percent of the market.
The proposal would affect about 8 percent of those now receiving Medicare benefits.